While management emphasised that most branches were open, union leaders argued that 80 per cent of the network suffered and that eight out of 10 Barclaycard staff had walked out.
Jim Lowe, assistant secretary of the Banking Insurance and Finance Union, predicted an even stronger response on Monday when employees are due to strike for a second time. Staff will also be banning overtime over the weekend.
Sister union UNiFI said the industrial action had cost Barclays tens of millions of pounds and claimed that up to 28,000 employees had joined the stoppage.
Mr Lowe pointed out that Barclays had admitted that 200 branches were forced to shut yesterday, but contended that the figure was "substantially higher" with more forced to close at peak times or shut early because of a lack of staff. Branches which stayed open were only able to offer a "very restricted" service with many being staffed with agency or casual workers.
Mr Lowe said that bank employees were not the most militant workers and the fact that they had walked out showed how angry they were. "The devastating impact of this first action has given confidence to those staff who didn't come out today. They'll be joining their colleagues on Monday."
A spokeswoman for Barclays poured scorn on union claims. She said 5,000 employees at most had joined the action. Only 209 out of 1985 branches had been closed and they were shut for security reasons. There was no significant impact on Barclaycard or the telephone banking service, she said.
The spokeswoman conceded however that there was disruption in parts of the north west of England, south London and South Wales.Reuse content