Southside House, one of Wimbledon’s most curious visitor attractions, opened its doors to the public for the first time exactly 31 years ago in January 1982.

Home of war hero Major Malcolm Munthe (1910-1995), the house at No 3 Woodhayes Road had just undergone three years of restorative work and was ready to show off its extraordinary collection of paintings and royal memorabilia – but only in wintertime on Monday, Wednesday and Friday afternoons.

Those fortunate enough to be shown around for a £1 ticket were treated to a stunning display of portraits by Van Dyck, Reynolds, Gainsborough, Hogarth, Raeburn, Burne-Jones and others.

Alongside these were personal items said to have belonged to royalty over several centuries which had happened to fall into the possession of Major Munthe’s ancestors.

The house itself was said to have been built in 1687 by Robert Pennington, a former royalist supporter of King Charles II during his exile in Holland, who had commissioned Dutch architects to convert it from a farmhouse into a stately home.

As no historical documentation existed to confirm this it caused some dispute between the Major and Wimbledon Society historian Richard Milward. Nevertheless the sheer fascination of the place and its contents could only expand its appeal in the years to come.

Major Munthe, who worked for Britain behind enemy lines in occupied Norway during World War 2, was the younger son of best-selling writer and personal physician to the Queen of Sweden, Axel Munthe (1857-1949).

After many years of medical practice in Sweden, France and Italy, Axel had moved to England where his wife, Hilda Pennington-Mellor, had inherited Southside House. There they brought up their two sons, Viking and Malcolm, and Axel wrote The Story of San Michele, a book of medical memoirs which sold vast numbers in numerous languages and remains in print to this day.

Hilda’s life was equally colourful. She had been courted as a teenager by the outrageously stupid King Alexander Obrenovic of Serbia who alienated his subjects so much that he was barbarously assassinated along with his unpopular wife.

When his mother, former Queen Natalie, later heard that Hilda was to marry Axel Munthe, she gave her a collection of Alexander’s family heirlooms. They are among the exhibits still on show at Southside House.

Other, perhaps more apocryphal, items in the collection over the years have included a comb said to have been used by Queen Anne Boleyn before her execution and a necklace worn by French Queen Marie Antoinette before she too lost her head.

Lady Emma Hamilton is also said have performed “attitudes” at the house in the days when she and Lord Nelson were living at nearby Merton Place. More historically certain were visits by Frederick Prince of Wales in the mid 18th century – an entire room is still maintained as his bedchamber - and two generations of the Wimbledon-based John Murray publishing dynasty.

Successive John Murrays had discussions in the Southside House garden with Lord Byron in the early 19th century and Axel Munthe himself a century later.

One fascinating feature has always been the Powder Room. This was where 18th century wigs were refreshed as the wearers put their heads through a hole in a wall and a servant powdered them from the other side, stopping the powder going everywhere.

That was also the time when the Duke of Wharton, black sheep of the family, performed outrages as a Hellfire Club member and kept a monkey dressed as Satan under his coat.

The building suffered severe bomb damage during World War 2 and Hilda moved all the earliest letters and documents to the family’s other house in Herefordshire. However, as luck would have it, that was also bombed and the papers were lost. Hence the dispute years later between her son and Richard Milward.

Southside House is run these days by the Pennington-Mellor-Munthe Charity Trust, serving partly as a residence but mainly as a museum hosting tour groups as well as cultural events such as lectures, concerts, and literary talks.

Another disaster hit the place in November 2010 when fire swept through part of the building. Fortunately, millions of pounds worth of artworks were rescued but it was months before visitors could return.

However, return they did, and Southside House is now available for events throughout much of the year.