The campaigner arrived for the ceremony in Berkshire with his wife Lady Suzanne Sercombe on Tuesday.
Sir Alan, who founded the Justice for Subpostmasters Alliance, received his knighthood for exposing the Horizon IT scandal.
He is one of more than 550 claimants who have brought legal action against the Post Office.
Over 700 branch managers were given criminal convictions between 1999 and 2015 after faulty Fujitsu accounting software, Horizon, made it look as if money was missing at their branches.
It has been called the most widespread miscarriage of justice in UK history.
A public inquiry into what happened is now in its final stages and due to conclude in November.
Speaking after receiving his knighthood for services to justice, Sir Alan said: "[The Government] haven't been in contact about what they're proposing to do yet.
"We think we've come to a standstill with most of the schemes in that they don't seem to be working, they seem to be failing now."
He said he original claimants are now calling on the Government to set a deadline for the initial GLO compensation scheme.
"We're wanting a completion date guaranteed by the Government for the end of March next year, and it's quite achievable, according to legal discussions I've had," he said.
"I think we've got to get rid of the bureaucracy that's holding the whole thing up and driving it into the ground, and it's proving such a headache for so many of the victims who are still suffering after so many years."
He went on to say: "The Post Office is as bad as ever. The financial redress schemes are just not working to the extent that they should, and it's just a mess.
"It needs to be taken out of Government's hands, and it needs to be put into an organisation that can resolve things very, very quickly because it's gone on too long, and people are still suffering."
Sir Alan previously turned down being made an OBE while former Post Office chief executive Paula Vennells held on to her CBE award because he said it "felt wrong", but calls for him to be knighted after Ms Vennells returned her honour were backed by No10 earlier this year.
Sir Alan said it felt "most unusual" receiving the royal honour, but added: "I accept it gratefully, but not just for myself, but for the whole group, and for everything we've all been through.
"If it gives me an extra sort of stick to beat the authorities over the head, so be it - I'll put it to good use."