Zara and Mike set to tie the knot at church on Royal Mile

There is speculation the couple will tie the knot at the Royal Mile church on July 30, just three months after Prince William marries Kate Middleton at Westminster Abbey.

And the wedding reception could be held at the Palace of Holyroodhouse.

A spokeswoman for Ms Phillips, the 29-year-old daughter of Princess Anne, insisted nothing had been finalised.

But a couple who had been due to marry at the Canongate Kirk on July 30 were today said to have been forced to rearrange their wedding to make way for the royals.

Capital pair Cherith Harrison and Gregg Walter, both 27, are understood to have switched their ceremony to Greyfriars Kirk on the same day.

And father of the bride Robert Harrison, managing director of a car dealership in Peebles, was quoted saying they had been "quite happy" to step aside for Ms Phillips.

He said the wedding had been planned for months, but the switch had been "easily done".

Canongate minister the Rev Neil Gardner said he was not in a position to comment on the speculation, but he added: "I'm sure there will be an announcement."

Ms Phillips and Mr Tindall announced their engagement just last month, five weeks after the news broke that Prince William and Ms Middleton were to marry.

The couple have been together for seven years after meeting through Ms Phillips' cousin, Prince Harry, in a Sydney bar during the 2003 Rugby World Cup.

Ms Phillips was said to be "desperate" to get married in Scotland in the summer.

The Canongate Kirk is the parish church for the Palace of Holyroodhouse and the Queen attends services there when she is staying at Holyrood.

Princess Anne married her second husband, Commander Timothy Laurence, at a private ceremony at Crathie Kirk, near Balmoral, in 1992.

A royal wedding in Edinburgh would be expected to attract crowds of well-wishers to the Capital and swell tourist numbers.

A Buckingham Palace spokeswoman said: "We would not comment on speculation at this time. Nothing has been announced."