The letters of patent themselves are made of goat's skin vellum, inscribed with 22 carat gold leaf and take two years to prepare. A coat of arms for a married couple costs £4,900, while single people can expect to pay between £2,450 and £3,400.
Successful applicants are awarded a grant towards the cost of preparing the document from the College of Arms.
Mr MacNichol first learnt of his eligibility after he joined the British Midland Institute of Genealogy and Heraldry last year.
"When I first went along to the society's meetings it was just to fuel my personal interest in the subject," he said.
"It was there I met Adrian de Redman, the city's honorary armourist, who suggested I might be eligible for a coat of arms.
"I've got a very strong sense of family tradition and l love history, so I put in a petition to the College of Arms. Two months later I was told my application had been accepted.
"We never thought this was possible and certainly didn't realise we'd be the youngest couple in Britain to have their own coat of arms."
College of Arms officials may have heard about the legal agent's exploits on a memorable trip to the Vatican, in Rome, in 1987.
Mr MacNichol, then aged 22, embarked on a charity bike ride to deliver a letter from parishioners at Knowle Church - which urgently needed roof repairs - to the Pope.
While crossing the Swiss Alps his front wheel became stuck in an railway track and he was flung off the bike and ended up in hospital.
"I didn't get to meet the Pope but at least I did what I had to, which was deliver the letter," he said.
Adrian de Redman, who is also a member of the Institute and was appointed honorary armourist for Birmingham in 1982, said the average combined age of couples awarded coats of arms is usually more than 90.
The law changed in 1995 permitting both husband and wife to have individual designs, rather than just the man.
As armourist he liaises with the College of Arms over many of the 200 applications it receives each year.
"These are nothing like the generic family shields you can pick up at market or on holiday, there is a rigorous process for all applicants," said Mr de Redman.
"Robert Noel, the Lancaster Herald, has the final say on each one and it's his decision whether or not to grant the award.
"These aren't just for professors or the 'great and the good', a lot has been done to take the snobbery out of this tradition.
"I think it's fantastic that a couple like Alistair and Joanne can illustrate that, and prove it's not just for 'fuddy duddies'."
