Between 1999 and 2015, hundreds of sub-postmasters were wrongfully prosecuted after the faulty Horizon IT accounting system made it appear that money was missing from branch accounts.

Sir Alan, who starred in an ITV drama that brought the scandal back into the spotlight earlier this year, leads the Justice for Subpostmasters Alliance and gave evidence to a parliamentary committee on Tuesday.

The hearing is looking at speedy and fair compensation for victims of the Post Office scandal and a key point for Sir Alan, which he mentioned earlier, is that the Government must set timescales for compensation payments.

He told MPs he had written to the Prime Minister twice in the past month to say it “must be finished by the end of March 2025”.

A No 10 spokesman said the Prime Minister had responded to Sir Alan earlier on Tuesday and added the Government was committed to swift compensation for victims but was wary of setting an “arbitrary cut-off” date that could lead to to the failure of some plaintiffs.

“We want repairs as quickly as possible,” he said. “What we don’t want to do is set an absolute cut-off date that would result in some claimants missing the deadline.

“But every eligible postmaster should receive substantial compensation by the end of March.”

Activists criticized the time it took for those affected to receive compensation. Many sub-postmasters were wrongfully sent to prison for false accounting and theft, and several others were financially ruined. Some died waiting for justice.

The Prime Minister’s spokesman said that as of October 31, around £438m had been paid out to more than 3,100 claimants across the four compensation schemes.