The award was confirmed and presented during a special West Norfolk Council meeting held at the Lynn town hall on Thursday evening.
And Dr Richards, who received a standing ovation following his Freeman’s speech, said: “That’s something that happens once in a lifetime.
“It’s something that makes you very proud and humbled.”
Dr Richards, who is chairman of of the North End Trust which operates True’s Yard and Norfolk’s deputy lieutenant, has twice served as borough mayor and was a councillor for 12 years between 1991 and 2003.
While groups such as the Lynn Air Cadets and RAF Marham have been awarded the Freedom of the borough in recent years, he is the first individual to receive such an honour in West Norfolk since 1969.
Only 16 people received the accolade throughout the whole of the 20th century and the last Freeman of the area to die was the Queen Mother in 2002.
Dr Richards admitted that he had wondered whether he deserved the award, the details of which were first made public in a February council report.
But he said he was especially pleased to receive the honour because of his love for Lynn and Norfolk as a whole and hopes to be able to use his new status for wider benefit.
He said: “It will give me more strength and a boost for the future.
“It will make me more determined to make a contribution.
“I feel it will give me more of a push, perhaps more influence and if you have influence you should use it for the common good.”
Council leader Nick Daubney revealed the idea of honouring Dr Richards had been in the authority’s thoughts since early last year and attracted widespread support.
He said: “He was born in Lynn, educated in Lynn and came back to Lynn after university.
“I don’t think there’s a cause that Paul hasn’t been involved with and many of those he’s taken a lead on. As a borough, we owe him a lot and this is a way of recognising that.”