Queen's royal approval for 'living in sin'

Cohabiting is the same as marriage - official. While some will, no doubt, argue that this view typifies a modern decline in moral standards, it comes from a person of the highest social stature: the Queen.

Peers filling in applications to attend this summer's royal garden parties and requesting tickets for family members were put in no doubt about Buckingham Palace's perception of relationships these days. The form includes the notation: "NB living with partner = married."

As someone about to celebrate her diamond wedding anniversary, the Queen is considered a shining advertisement for the institution of marriage. Yet she has quietly let it be known that, in the eyes of the Royal Household, co-habiting now has equivalent status.

Yesterday, politicians were speculating that the Royal Household's decision to move with the times might have been influenced by goings on within the Royal Family.

The Queen's granddaughter, Zara Phillips, lives with her boyfriend, the rugby player Mike Tindall. The winner of the BBC Sports Personality of the Year, who gained the individual gold in the world three-day event championship, was not coy about the fact that she also lived with her former boyfriend, the jockey Richard Johnson, posing for photographs in Hello! magazine.

The forms, entitled Her Majesty's Garden Parties 2007, specify that members of the House of Lords may bring up to two unmarried sons or daughters between the ages of 18 and 25 to the Buckingham Palace party.

Children co-habiting with their partners will be considered married, and cannot come. One perplexed peer, anxious to meet tomorrow's deadline for tickets, said the rule could raise awkward questions within the family.

"I worry about Her Majesty's garden party in July. How many nights a week can my daughter spend with her boyfriend and still be allowed in now Buckingham Palace says living with partner equals married?" he asked.

Buckingham Palace declined to comment on the ruling. But MPs say the decision to consider co-habitees on the same terms as married people showed the palace was more in touch with how people live than many might think.

Lorely Burt, equalities spokesman for the Liberal Democrats, said: "I am glad the palace are up to date with how people live in Britain today," she said. "I wonder whether the Queen will extend the same generosity when it comes to domestic arrangements for her own grandchildren. I sincerely hope so."