£15m of client monies moved to Barclays with no break in the records

01The challenge

Warwick decided to move half of its client-money accounts, roughly £15m, from Barclays UK to Barclays International. The new accounts were virtual accounts under one header account with a single IBAN, with money allocated by matching the payment reference. BOSS had to keep a continuous record for every account through the move, then work with both banks side by side: each payment instruction, bank statement, balance check and new-account request now came in two formats. A duplicated account record would have been costly to unpick.

02What we did

1. 01Design: the four points where BOSS met the bank, from payment instructions to new-account requests, mapped for both providers
2. 02Build: parallel adaptors that recognise which bank a file came from, validate it and feed one shared processing component, with outgoing payments split into one file per bank
3. 03Build: each old account record replaced by its virtual account in one atomic, repeatable background command, so the two could never coexist
4. 04Rehearsal: the transfer tested against £1 dummy accounts and simulated bank outputs at every step
5. 05Transfer: every instruction to the bank verified as Warwick ran the move, so any failure was caught where it happened

03What we built

• Payment instructions generated per bank automatically
• Allocation by virtual-account payment reference
• Reconciliation against either bank's balance list
• Atomic, repeatable account replacement
• Validation of bank CSV and SIF files
• AI model trained on BMAP transaction narratives

04The result

The transfer ran with minimal issues and very little data clean-up: problems were caught at the step where they occurred and resolved in real time. BOSS kept one continuous financial record across both banks, and when Warwick later decided to move its client accounts to NatWest, the same adaptor approach was used to normalise the new bank's data.