London: As a tribute to Prince William and his to-be-bride Kate, the Royal Mail in Britain will release a new set of stamps. The royal wedding is to take place on April 29.

The official engagement portraits of the couple, sharing a hug, by photographer Mario Testino will be used on two different versions of the stamps. A casual picture of the couple will go on the new 46p first-class stamp and the more formal image on a 1.10 pounds one for overseas use.

William becomes the first of the Queen's grandchildren to have a wedding marked in this way although when Charles and Diana married in 1981, two new stamps were issued, the 'Daily Express' reported.

The second-in-line to the British throne has featured on Royal Mail stamps twice before -- to mark Queen Mother's 100th birthday and later to mark his own 21st birthday.

The new stamps will come in a sheet of four: Two for first-class mail and two 1.10 pounds items. Post offices will sell them from April 21 -- the Queen's birthday -- but they can also be ordered via Royal Mail's website from April 7.

Prince William (28) and Kate (29), who got engaged in October last year, are to tie the knot at Westminster Abbey in London on April 29.