It's lasted longer than the marriage! Slice of Charles and Diana's wedding cake goes up for sale 40 years on still wrapped in clingfilm

A large slice of Charles and Diana's wedding cake has emerged for sale 40 years after they tied the knot - and it is still wrapped in cling film.

The impressive portion of icing and marzipan base is decorated with a Royal coat of arms in red, blue and gold.

It was given to Moyra Smith, one of the Queen Mother's employees at Clarence House, following the 1981 ceremony.

The slice, which measures 8ins by 7ins and weighs 28oz, has been preserved in cling film in an old cake tin for four decades.

The impressive portion of icing and marzipan base is decorated with a Royal coat of arms in red, blue and gold

A large slice of Charles and Diana's wedding cake has emerged for sale 40 years after they tied the knot - and it is still wrapped in cling film

It was kept by Moyra's family until 2008 when it was acquired by a collector who is now selling it with auctioneers Dominic Winter, of Cirencester, Gloucs.

In total, 23 official cakes were made for the wedding, including a centrepiece 5ft tall layered fruitcake weighing 225lbs.

This slice is believed to have been cut from a cake distributed to staff at Clarence House to thank them for their efforts.

The cake tin where the slice has been kept has a note which reads: 'Handle with care. Prince Charles and Princess Diane's wedding cake, M.C Smith.'

The slice is tipped to fetch £500 when it is sold alongside an order of service for the St Paul's Cathedral wedding and Royal Wedding Breakfast programme.

The auctioneers described the slice as a 'unique Royal keepsafe' but advised against eating it for health reasons.

It was given to Moyra Smith, one of the Queen Mother's employees at Clarence House, following the 1981 ceremony. The slice, which measures 8ins by 7ins and weighs 28oz, has been preserved in cling film in an old cake tin for four decades

Chris Albury, specialist Royal memorabilia valuer at Dominic Winter, said: 'I still wouldn't recommend eating it but after 40 years it's clearly destined to last.

'It's a curious and unique keepsake celebrating a royal wedding that holds an enduring fascination with British royalty aficionados worldwide.'

In 2014, a slice of their wedding cake was sold for $1,375 (£990) in an auction held in Los Angeles, California. 

The cake was still wrapped in its original wax paper inside the original white and silver presentation box which had 'Buckingham Palace 29 July 1981' written on it.  

In 2014, a slice of their wedding cake was sold for $1,375 (£990) in an auction held in Los Angeles, California 

The 'wedding of the century' was watched by an estimated global TV audience of 750 million people, with street parties held throughout the United Kingdom to celebrate it.

However, the Royal couple's relationship was visibly strained by the late 1980s with rumoured affairs on both sides.

They separated in 1992 and divorced in 1996 after 15 years of marriage. Diana died aged 36 in a car crash in 1997.

The sale takes place on August 11.