Apologising for the serious disruption, Royal Mail, which handles 16 million items a day in the capital, said that only 5% of about 25,000 postal staff had turned up for work and it would take up to five days to clear the backlog.
But it claimed that more than 60% of the 5,000 counter-staff had turned up for work, with nearly all post offices open. It also claimed that more than 6,500 "volunteers" had kept the special delivery service going and maintained collections and deliveries of business mail.
The CWU disputed the claims, arguing that deliveries and collections had been halted and counters had been kept open only through the presence of managers.
"It's been very solid and it doesn't look as if anyone has crossed picket lines," CWU officials said. "At Mount Pleasant, where normally 3,500 work, there's a couple of hundred managers running just a skeleton service."
The strike, which follows a narrow vote in a national ballot against industrial action on pay, is over CWU demands for London weighting (cost of living allowances) to be increased to £4,000 a year in both inner and outer areas.
Royal Mail, which lost £611m last year, has agreed to a £300 unconditional rise to £3,784 (for inner London) and £2,667 (outer London) under its 14.5% 18-month pay and productivity offer.
Adam Crozier, its chief executive, said the overall £340m deal was "the limit of what we can afford". But amid hints that a fresh stoppage could be staged on October 16, alongside one by London local government workers, the CWU said the offer was "insulting".
