It follows a landmark day at the Court of Appeal in London last Friday, when 39 subpostmasters who were convicted and even jailed based on data from the defective Horizon accounting system had their names cleared.
Solicitor Neil Hudgell, of Hull-based Hudgell Solicitors, who has helped 33 former subpostmasters to clear their names through the courts so far, said they had received 20 new inquiries over the weekend.
The 51 cases he is currently dealing with include 38 relating to people convicted in Crown Court, which were submitted direct to the Court of Appeal last week.
A further 13, relating to convictions in magistrates courts, are already with the Criminal Cases Review Commission.
Mr Hudgell said the latest cases included “yet more heartbreaking stories of lives unfairly destroyed”.
He said: “Following the events of Friday, and the widespread media coverage, the wider public is now becoming much more aware of the depth and significance of this scandal and how lives have been completely destroyed.
“The subpostmasters have huge support in terms of seeking answers and compensation over what happened to them and the Government must be seen to deliver in both regards.”
It came as former Post Office chief executive Paula Vennells quit as a non-executive director of high street chains Morrisons and Dunelm, as well as stopping her duties as an ordained Church of England minister.
Ms Vennells, who was made a CBE for “services to the Post Office and to charity” is an associate minister in Bromham, Oakley and Stagsden, Bedfordshire.
In brief updates to the London Stock Exchange, the firms said she would be leaving the roles, which include responsibilities for setting executive pay and upholding corporate responsibility.
She took home £89,000 in fees from Morrisons and £30,000 from Dunelm in the past year, according to the latest accounts.
Ms Vennells issued an apology on Sunday as she announced that she would be stepping back from her regular church duties.
She said she was “truly sorry for the suffering” caused to the 39 subpostmasters, adding: “It is obvious that my involvement with the Post Office has become a distraction from the good work undertaken in the Diocese of St Albans and in the parishes I serve.
“I have therefore stepped back with immediate effect from regular parish ministry, and intend to focus fully on working with the ongoing Government inquiry to ensure the affected subpostmasters and wider public get the answers they deserve.”
The Bishop of St Albans said it is “right” that Ms Vennells “stands back from public ministry” following the ruling, adding: “As the son of a former subpostmaster I express my distress at the miscarriage of justice that so many subpostmasters have suffered”.
Mr Hudgell repeated his calls for a public inquiry to ensure Post Office managers are fully questioned under the rules of evidence and held to account.
He said: “I’m sure many of my clients welcome Ms Vennells removing herself from these positions today, but given she left the Post Office with hundreds of thousands of pounds in bonuses just months before this scandal was fully exposed by the courts, I am sure they will share my view that it shouldn’t have taken her this long to do so.”