Postal workers have taken to picket lines as a fresh 24-hour strike went ahead in a bitter row over pay and jobs.
The Communication Workers Union said up to 130,000 of its members walked out at 7pm on Thursday, following an earlier stoppage last month.
At midday on Friday, postal workers plan to arrive at the Royal Mail's head office in London on a red open-top bus.
They will hand over an oversized open letter addressed to Royal Mail chairman Allan Leighton, calling for a return to negotiations.
The union has rejected a 2.5% pay offer and warned that the Royal Mail's modernisation plans will lead to the loss of 40,000 jobs.
Union representatives met with Royal Mail earlier this week in a bid to begin fresh talks.
But the union later said: "Disappointingly, Royal Mail simply concentrated on reiterating their previous offer that the workforce has already overwhelmingly rejected."
The Royal Mail has said it was "deeply disappointed" that another strike had been called, warning of further disruption for customers.
It has said it was ready to meet the union at any time to explain its offer.
Business leaders have called on the Government to intervene in the dispute.
