5. Mary Queen of Scots' sick note

Mary Queen of Scots - Sympathic with gout

This letter was discovered at Blair Castle in Ayrshire, one of the oldest continually lived-in Scottish castles. Dated March 14, 1554, the note was written by Mary Queen of Scots to excuse the then Laird of Blair from his duties at court, due to chronic gout.

The letter more than doubled its estimate in the March 2012 sale, achieving an impressive £5,000. Check out the full story here.

We have a remarkable collection of King Henry VIII signed manuscripts currently on offer to collectors. This personal divorce plea from the tyrannous king to Pope Clement VII perfectly frames a crucial event in British history.

4. Queen Mother's 'Gin & Dubonnet' letter

All in a day's work for the Queen Mother

In 2008, an auction of royal memorabilia was held following the death of the Queen Mother's favourite servant, William Tallon. Also known as Backstairs Billy, Tallon served the royal family for 52 years and kept all of the correspondence he received from them over the years.

Of the many gems that surfaced in the auction, perhaps the most charming was a letter from the Queen Mother which states: "I think that I will take two small bottles of Dubonnet and gin with me this morning, in case it is needed."

The letter sold for £16,000, well above its estimate of £3,000.

3. Royal wedding cake

The first slice from the Duke & Duchess of Cambridge's wedding

Cake from royal weddings is highly desirable to some collectors. As we have seen from the recent marriage of Prince William to Kate Middleton, royal weddings attract a huge amount of attention and royal fans will clamour to get a slice of the action.

Fragments of Queen Victoria's wedding cake were sold by Christie's for £70 in 1974, 134 years after her marriage to Albert. They later featured in an exhibition at Windsor Castle.

PFC auctions saw record prices for its slices, with a piece of Charles and Diana's cake selling for £1,756, a 16.20% pa rise on the last piece, which sold in 2008. The May 24 sale also saw the very first piece of Kate and Wills' wedding cake achieve £1,917, setting a benchmark for the slices that will undoubtedly surface in the years to come.

2.  Regal undergarments

The pair of knickers left behind by Queen Elizabeth II

You may have recently seen a pair of Queen Elizabeth II's pants in the press, when they sold for £11,390 on Ebay. The fine silk bloomers were purportedly left on a plane by the British monarch on her 1968 visit to Chile. 

Yet they weren't the only royal knickers to leave their mark on the collecting world. A huge pair of Queen Victoria's bloomers sold for £9,375 in November 2011, while Vienna's 2012 annual imperial auction saw a pair of undies worn by Austrian Emperor Franz Joseph make $8,000 - double their pre-sale estimate.

1. Wallis Simpson Cartier bracelet

The most lavish piece of royal memorabilia

This item has to top our list, as it represents not only the most dramatic royal love story but also the height of regal lavishness.

The Cartier-designed onyx and diamond bracelet was presented to Wallis Simpson by Edward VIII, following his abdication from the British throne. Edward was forced to give up his seat as King when he proposed to Simpson, the twice-divorced American socialite.

The bracelet sold for £4.5m at Sotheby's in 2010, becoming both the most expensive bracelet and the most expensive Cartier item sold at auction.

Paul Fraser Collectibles has a superb range of royal memorabilia currently in stock. This charming photograph of the royal family, signed by Queen Elizabeth and Prince Philip makes a wonderful jubilee collectible.

Investment-grade royal memorabilia is set to receive a boost over the coming months, find out why here.