Sir Alan Bates, the leading campaigner for subpostmasters in the Post Office Horizon IT scandal, will receive his knighthood at Windsor Castle on Wednesday.

The 70-year-old, of Llandudno in north Wales, is one of more than 550 claimants who have brought legal action against the company, with a public inquiry into what happened in its final stages.

He was recognised in the King’s Birthday Honours in June for his services to justice, having founded the Justice for Subpostmasters Alliance.

More than 700 subpostmasters were prosecuted by the Post Office and given criminal convictions between 1999 and 2015, as Fujitsu’s faulty Horizon IT system made it appear as though money was missing at their branches.

Sir Alan was portrayed by actor Toby Jones in the ITV drama Mr Bates Vs The Post Office, with the four-part mini-series helping to renew attention on the scandal.

Reacting to his knighthood in June, he told the PA news agency: “It was a bit of a surprise, it sort of came out of the blue.

“I’m quite honoured by it – to be recognised for the work that I’ve done over the years.

“It’s been a hard slog over many years.”

Sir Alan added he hoped the honour would be “another string to my bow to help me go forward and get some finality for people”.

He previously turned down being made an OBE while ex-Post Office chief executive Paula Vennells held on to her CBE award because it “felt wrong”, but calls for him to be knighted after Ms Vennells returned her honour were backed by Number 10 earlier this year.

Bafta Award-winning writer, director and producer Armando Iannucci and former Olympic sprinter Anita Neil are among those also being honoured at the investiture ceremony.

Iannucci, 60, who is best known for helping to create the Alan Partridge character and political satire The Thick of It, will be made a CBE for his services to film and television.

He won two Baftas for the works in 1998 and 2010 respectively while he also picked up two Emmys for the US political spin-off series Veep.

Neil will be made an MBE for her services to athletics having become the first black woman to compete for Great Britain at an Olympic Games in 1968.

She ran in the women’s 100 metres and 4×100 metres relay team in Mexico City and at the Games in Munich four years later.