Jim Armitage: RBS takes heroic gamble before Brexit poll

Next time your online banking is running slow or your financial trading software gets glitchy, blame the Brexit referendum.

Banks have deliberately delayed the routine patching-up and upgrading of their IT systems for weeks ahead of Thursday’s vote. They’re worried that a victory for the Leave campaigners could spark a surge of activity by customers on Friday that may topple any untested new IT programmes.

Contingency planning is everywhere. Some banks are filling their ATMs to the brim to make sure they don’t run out if the Brexiteers win and customers rush to make withdrawals. All branches are on red alerts not seen since the Scottish referendum.

In the trading rooms, banks and hedge funds will be heavily staffed on Friday to make sure their electronic trading programmes don’t go Brexit-berserk from abnormal spikes in volumes and prices. One trader says that there’ll be “four pairs of eyes on every algorithm”.

Yet while caution is the watchword everywhere else, RBS is trundling on this week with its plan to carve out the IT for its Williams & Glyn branches’ cash machines.

The bank, which has to split off 300 branches under EU competition rules, assures us this is simple, low-risk stuff.

But given its recent track record of catastrophic IT failures, it seems a rather heroic gamble.