Mr Madden is one of 12 lay clerks at the College of St George's Chapel and therefore sings for the Queen at least five times a year.
He has been in Dunedin visiting his parents, Richard and Robyn Madden.
Windsor Castle is where the Queen and Prince Phillip spend 80% of their year and Mr Madden is often called on to sing at royal baptisms, birthdays, anniversaries and private dinners.
The Queen, he says, likes Elgar but in moderation, and he recalls that after a performance marking the 660th anniversary of the college, the Queen was heard to remark: "It went on a bit."
Mr Madden said it took three months to get his security clearance allowing him access to the castle grounds, where the royals roam with their corgis, golf clubs, children and grand-children.
Last year, Mr Madden sang a solo written by his father as part of the thanksgiving service for the late Sir Edmund Hillary, who was one of the chapel's 25 Knights of the Garter.
In April, Mr Madden was married in the chapel to another former St Paul's choir member, Elisabeth Tyrrell, and the couple have free use of a four-roomed home in the castle walls.
Mr Madden describes the job as "part time" but he is required to sing eight times over a six-day week.
He also performs in some other musical engagements.
Singing on the weekend had restricted his availability for the Royal Household Cricket Club, which plays on a picturesque ground not open to the public.
But he is one of the 34 members of the golf club run by Prince Andrew, whom Mr Madden described as a "golfing nut".
Nick Madden began singing as a member of St Paul's Cathedral choir in Dunedin.
He progressed to a position at Ely Cathedral in England in 2003 before winning a place at St George's two years ago.
The only non-English lay clerk, Mr Madden found himself one of 48 tenors put through a rigorous audition that tested not only singing ability but the applicants' suitability in the eyes of the other clerks.
The audition came down to two.
"I was lucky the guy I was up against was pretty boring."
Now, provided he looks after his voice, he can continue in the job as long as he wants.
One lay clerk, due to retire, has been singing for 35 years.
Mr and Mrs Madden left Dunedin yesterday for Nelson and return to England on Thursday.