John Key talks flags and rugby with the Queen

John Key and Queen Elizabeth talked flags and rugby. Photo / AP

Prime Minister John Key has met the Queen at Windsor Castle - and rugby and referendums were the hot topics.

This morning (NZT) Key made a scheduled trip to the royal residence in Berkshire ahead of an afternoon at tomorrow's Rugby World Cup final between the All Blacks and the Wallabies at Twickenham.

Photo / AP

Before the meeting, Key had made it clear New Zealand's flag debate would be brought up with the Queen at some point, although it was his belief she does not consider the issue of our potential flag change to be controversial and is happy to leave it up to Kiwis to make a decision.

With the Queen's dogs wandering around, Key stood at the doorway of a sitting room and bowed before Her Majesty, before the New Zealand leader opened the small-talk.

John Key sits with Queen Elizabeth. Photo / AP

"Lovely to see you again, thank you very much for having us here, it's wonderful," Key said.

"It's going to be an exciting weekend with the rugby, of course."

Last month Queen Elizabeth became Britain's longest-serving monarch, her 63 years at the helm taking her past the record set by Queen Victoria.

Key, meanwhile, has warned Kiwi taxpayers to brace themselves for some hefty ministerial hotel bills in the next expense release - all because of the Rugby World Cup final in London.