In an example of more revolving doors in London’s heated fintech space, TechCrunch has learned that Curve co-founder Tom Foster-Carter is joining Monzo. As of Monday, he takes up the role of COO at the digital-only challenger bank, with some aspects subject to regulatory approval.

At Curve, a platform that lets you consolidate all your bank cards into a single card and manage your money, Foster-Carter held the position of Head of Operations, which I understand is being filled by newly promoted Rona Ruthen. Prior to Curve, he was COO at kids banking app Osper, as well as spending three months at another London-based challenger bank Tandem.

In a brief call with Foster-Carter this morning, he confirmed that he has left Curve and taken up the COO position at Monzo . He stressed that he remains friends with Curve founder and CEO Shachar Bialick, who recruited him to co-found Curve in March 2015 in addition to Anna Mostyn Williams, who has also since left the startup.

He said that after raising Curve’s Series A the pair agreed it was best to part ways. He remains bullish on Curve and the startup’s team (where he remains a minority shareholder), but is also excited to join Monzo, which, based on its weekly growth, he says is definitely onto something.

“Curve co-founders Shachar Bialick and Tom Foster-Carter have agreed to part ways amicably, with Bialick staying on as CEO and Rona Ruthen being promoted to Head of Operations,” said Curve in a statement. “Ruthen was previously Payments Operations Manager at Payoneer and brings a fantastic range of fintech skills and experience to the role. With the Series A funding round recently closed, the business is now focused on scaling up on its mission to simplify the way people spend, send and see their money”.

Zooming out a bit further, it is interesting to note that both Curve and Monzo — and almost every other recent consumer fintech play — are aiming to become the single convergence platform to help you manage your money via a central UI that connects to all of the other financial services you use. However, the difference in product strategy (or how they’ll get there) couldn’t be greater.

Bialick has always insisted that nobody needs to become a bank, which brings with it significant extra capital and regulatory overhead. Instead the advantage of Curve is that it is a platform and UI layer than runs purely on top of existing banking and payment rails and doesn’t ask you to switch banks and is agnostic regards where your money resides. That also makes it a potential partner to existing incumbent banks, as the recent Series A backing from Santander Ventures points to.

In contrast, Monzo co-founder Tom Blomfield believes that the best “attack vector” — as he likes to call it — is the humble current account. It is only by building as much of your own banking rails as possible can you innovate fast and deep enough to provide a significantly better UX than what exists today, or that being built by other competing fintech upstarts.

This one has a long way to play out yet.

Article updated 11.13am PDT on 11th of August to remove additional comments attributed to Foster-Carter, and speculation regards Curve recruiting an outside COO.