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The Big Interview: Pleo CTO and Monzo veteran Meri Williams

On business continuity, microservices, and masking...

It’s been quite a career journey for Meri Williams from teenager building satellite components in South Africa ("something I soldered is in space... it's all been downhill from there*" she jokes) to experienced CTO and non-executive director (NED). Williams is currently heading up a transformation at Scandinavian business spending startup Pleo, which provides payment cards and associated software for staff expenses, and over the years has built a reputation for forward-thinking technology deployments, as well as a keen focus on business continuity.

The CTO is perhaps best known in the industry for their time at Monzo, overseeing a 300% boom in team size as the upstart bank quadrupled its customer base to four million, but despite something of a recent portfolio career (Head of Engineering at M&S, CTO at healthcare startup Healx) that has included no shortage of digital natives, she actually cut her teeth during a decade at established consumer goods behemoth Procter & Gamble

In just under 10 years there she worked her way to Head of Operations overseeing its North Europe sites (finding time to do things like overhaul its internship programme along the way) first as a developer and then an architect, before they “outsourced everything, so I did programme and project management for a while and then they realised that they had outsourced a bit too much and brought some back. I ended up being the most technical person they hadn't outsourced [and] running the biggest SAP install in the world; I'm okay now" she says drily.

Joining The Stack on a Zoom, Williams is refreshingly direct and free of conversational agenda (some, not all, executives only want to talk about their Big New Product or Impressive Cloud Migration) in a wide-ranging conversation that hops cheerfuly from ADHD (they were recently diagnosed, as was her interviewer) to microservices, via Agile and continuity planning for “weird, unexpected things that nobody's got a plan for.”

CTO Meri Williams on deconstructing Deimos...

Williams is currently five months into a CTO role at Pleo, a Copenhagen-based fintech that was founded in 2015.

There, she is “leading the team through a bit of an evolution from some of the very typical challenges that you get in a company of that age; so a little bit of dealing with technical debt, a little bit of setting us up for the future… and largely thinking about scaling.” (Pleo, one of Europe’s fastest growing fintechs, has some 26,000 enterprise customers in 16 different countries. It issues company cards with individual and team spending limits and integrates with accounting tools like QuickBooks, Sage, or Zero for expense invoice management.)

What kind of technical debt does a cloud-native startup accrue, we ask innocently? (Quite a lot, as it happens, as can equally cloud-native apps like dating apps, as one recent DevOps-focussed interview highlighted…)

“[Technical debt at this level] is less about the infrastructure layer and more about the software layer” Williams points out, adding "it's super useful in the early days of a product, to build it as a monolith.

"But at a certain point, you don’t need playdough, you need Lego; a little bit more structure, more separation of concerns… we were hitting a point where that monolith sits on top of such a big data store that we couldn't keep making the server that the database was sitting on bigger and bigger and bigger. So in order to make sure we can keep scaling and keep serving our customers, we're breaking that down into its component pieces.

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“Technical debt is like financial debt” they add: “It's not a problem to sometimes buy something that you need and pay some interest on it. It's a problem when you put your mortgage on the credit card; when you're paying really high interest on something really major, that's when you end up in trouble…”

Pressed for a little more details, she says “Our monolith is called ‘Deimos’ (all the services at Pleo are named after moons) so we’re doing ‘Death to Deimos’; slowly deconstructing it essentially. So we take parts that are logical and pull them out into different services and different data stores under those services.

“The second major change is that we're moving to an API-first way of working; that's a fairly major change… We were very focused on what the UI was for the direct customer. But we're increasingly finding that we're one of many tools that a company uses, and integrating with those other tools is really important.”

(Pushed for a few more details, for example on databases of choice -- Monzo was a famously heavy Apache Cassandra user, as Meri Williams recalls, saying "we were really pushing the pushing the boundaries of what Cassandra was capable of being used for at the time; whilst I was CTO there, we hired some major contributors to the open source Cassandra programme, because we wanted those folks in-house so that we could deeply deeply understand the way Cassandra was going to cope under certain conditions" -- she says that Pleo is a big PostgreSQL user; distributed observability provider Honeycomb also gets a nod from the CTO.)

The Big Interview: CTO and NED Meri Williams

Pleo is having to make this shift to API-centricity after – like so many in the tech industry – it laid off around 15% of its workforce in late 2022. How is the company’s team finding having to do a lot more with less?

“We're not growing the team in number, but we are growing them in capability” says Pleo CTO Meri Williams.

“So we are doing a load of upskilling. We're doing 'deep coaching' and putting a couple of 100 people through a big programme of ‘how do you move from working the way that they traditionally have… how do we design great rest API's? How do we think of the API as part of the product… It's not just a technology initiative, it's not just us doing some training: it's us saying ‘this is a really important business need and here's the support for how you get there’” she adds.

It’s a very different experience and climate, she acknowledges, from the rampant scaling at Monzo or Healx which whilst exciting, can also “end up with some of the existing people feeling like they're being left behind or overshadowed by some of the folks coming in from outside. So that's always a sensitivity to be aware of…”

On D&I and the risk of burning out

A rightful priority for Williams has always been trying to help build diverse teams and nurture talent.

Diverse teams in IT and tech are still not the norm in most companies. What can leaders to do help shift that? “People who are under-indexed or under-represented in tech are like the future; we're here, we're just not evenly distributed, we tend to clump together a little bit” she says. “I've had plenty of teams that are 40% women and non-binary; that have got as many queer people in leadership as as non-queer people…

“It tends to be because we  know that not every environment is safe and not every environment is going to view our differences as a feature rather than a bug. So we tend to go where we think we will be appreciated for that. Having joined having joined player, my entire leadership team is men at the moment. They're not all white men, but they are all men. That's a that's an interesting and unusual situation for me. But there's definitely some folks in the next layer down who will progress up over the next couple of years.”

Being a queer woman comes with some pressures to be the constant figurehead, she admits honestly.

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“I’m the person the Daily Mail warns you about because I’m different in many different ways.

"I find that that, on the one hand, is a huge privilege, because I do end up being a role model, whether I like it or not, whether whether I want to or not –  just existing and being different in these ways is kind of a lot for people, and means a lot to them already. But it does add extra pressure as well, to make sure that the companies I'm at are doing well at diversity and equity and inclusion and belonging, and that they're investing in those things, because people tend to look at me and go, ‘ah, if you're there, it must be a good place to be’ and so I feel this sort of sense of honour that I need to make sure it is a good place to be. If I'm going to be a figurehead in that way, then I need to make sure that the reality follows the perception” she says reflectively.

Williams has done consulting for companies like Spotify and others on D&I over the years and says “everyone is ultimately asking ‘am I expected [to be] here? So for instance if you’re Muslim you want to see evidence that there's a prayer room, you don't want to have to ask about that; you want it to be volunteered information? Am I respected here? Are my differences going to be seen as features or as bugs? And then can I be myself and be successful here?” She adds that “it's a bit like… we talk about in the Autistic community that we have to wear these masks and pretend to be neurotypical, even if we're not. “And it just takes such energy, it can burn you out. So finding a way to be able to be yourself without having to spend all that time masking is really important.”

Perhaps a lesser known passion of Williams is business continuity – “a pet interest of mine”.

It's one that proved prescient: “I was very proud that at Monzo, I led a load of work on business continuity that culminated at the end of 2019 and was delighted that it paid off so rapidly, because then COVID happened, and we moved from being quite an in-person bank – a lot of people went to the office every day – to being fully distributed overnight with basically no problems, which was not the case for a lot of the other banks in London.”That focus, she says was born whilst working at P&G and regularly encountering some testing real-life scenarios: “I had responsibility for all of these different sites… there was the time where somebody nicked the copper cabling that provided internet to the entire town one of our plants was in and so it lost internet for a week: How do you run a plant when you don't have internet and when you can't use mobile phones, because it was a perfume factory and it could cause explosions if you had people on phones on the site?

“So what I did at Monzo was essentially take every team in every area and say, ‘we're going to run a Dr. Pepper workshop  [per the ‘what’s the worst that could happen?’ jingle] and say ‘what's the unexpected thing that would really mess us up? What if we couldn't get into the office ever again? That led us to just find a whole bunch of different things that would be a problem if we couldn't get to the office anymore, if certain key people weren't available for an extended period of time… then one-by-one we just went and closed those holes. [For example] there were special laptops that you had to use to access the Bank of England systems," she recalls.

"So we made sure that those that there was a spare laptop locked in an [external] safe so that if nobody could go to the office for a while somebody could still perform those duties. So it starts at a process level, but then ends in a load of technology and other improvements that I think are really interesting…”

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Before we wrap up, The Stack asks quickly about her NED experience. (She found it really fascinating being on the other side of the board table, right? So I've spent quite a lot of time on the exec side and was always just interested in what it would be like to be on the other side. So So I learned how to be a nerd by being a trustee at Stonewall, and you know, major charity like that it was really interesting to learn the ropes in terms of governance and everything else. But yeah, I've I've massively enjoyed my monad role of flagstone you know, Bing Bing, dropping into the business helping coach, the chief product officer and the and the VP of engineering. They have a similar kind of technical debt journey that they're on where they're modernising massively. And it's been, it's been really interesting. The the main tip I've got is probably to get a good mentor who can help you know, when you're overstepping back into exec style, action, because there is this line, you know, you're really meant to be independent, non executive. And if you've been an executive for a long time, that can be quite challenging to stop yourself from going into exec mode. And so that's the main, the main advice I've got is get a good mentor who can help you judge where that line is, and make sure you don't step over it and make sure that you're in the guiding and helping rather than the executing mode. Yeah.

What is it like going from executive to non-executive? Any tips for those making the leap? (Williams is a NED with cash deposit platform startup Flagstone.) She says: "I've massively enjoyed my NED role at Flagstone. They have a similar kind of technical debt journey that they're on where they're modernising massively. The main tip I've got is probably to get a good mentor who can help you when you're overstepping into exec-style action, because if you've been an executive for a long time, that can be quite challenging to stop yourself from going into exec-mode. So the main advice I've got is get a good mentor who can help you judge where that line is, and make sure you don't step over it and make sure that you're in the guiding and helping rather than the executing mode..."

*Her school had a tieup with Stellenbosch University, which developed Sunsat ,a 65kg microsatellite with a 15m GSD 3-band multi-spectral pushbroom image that was South Africa's first satellite developed completely by a team of South African engineers and launched by NASA on Delta II USAF in February 1999.

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