"You've got to have 22 years in the military and have a Long Service and Good Conduct medal.
"You're expected to be married, you have to maintain the dwelling between the walls of the Tower, and you must have been a Sergeant Major or Regimental Sergeant Major."
Mr Nolan said he was proud that he was chosen to be a Yeoman Warder after a competitive selection process.
"I'm the first and only non-British serving serviceman to become a Yeoman," he said.
"And there's a long history behind it all. The first Yeoman Warder went to the tower on the 15th of August, 1100.
"That's 200 years before the Maori arrived in New Zealand."
Mr Nolan said the job involved 65-70-hour work weeks, and that the "heavy and hot" State Dress could take up to 20 minutes to put on.
"But you get familiar with it, and though it's heavy and hot, it's a privilege to actually have one.
"We'd work for seven days and have two off.
"Seven on, two off, seven on and then we have a 3-day weekend."
In his spare time, Mr Nolan said he represented the New Zealand RSA.
"I was their man in Europe. So we got to go to some wonderful places and meet some special people."
Mr Nolan's wife, Dawn, said she was privileged to have had such amazing opportunities and experiences while living with her husband at the Tower of London.
"When we were living in the Tower I always felt like, yay that's where we live," she said.
"I had so much excitement for the fact that we were there.
"We went places and met people that we never would have met otherwise, and the Yeoman Warders' wives usually work too.
"I was a civil servant for the Ministry of Defence.
"It had its restrictions but, especially with the RSA's involvement, it opened up a whole new world for both of us."
Mrs Nolan said living in the Tower of London was "a real adventure" and she loved being able to travel across Europe.
"It's fun when you're young, but being older when you are visiting all these places, you've got more of an understanding of what they are.
"I think the first time that we met the Queen and the Royal family was a highlight. But it was just the whole experience that was a highlight really."
The couple are happy to be back living in New Zealand and now can spend more time with their children and grandchildren.
"There was an awful lot that we would have still loved to do over there but, after all, home is home," Mrs Nolan said.
"It's where we are supposed to be."