No series on the treasures of London would be complete without a mention of the Crown Jewels, housed – except when being used – under tight security in the same place they’ve been since the early 1300s – the Tower of London.

The jewels, which are described as a ‘working collection’, include the coronation regalia and feature some 23,578 gems  – the Imperial State Crown alone boasts 2,868 diamonds, 273 pearls, 17 sapphires, 11 emeralds and five rubies.

The regalia itself is made up of the crowns of the sovereigns, consorts and Princes of Wales as well as sceptres, orbs, rings, swords, spurs, bracelets, robes, and the oldest piece, a 12th century anointing spoon.

It and three steel coronation swords are the only pieces to survive the destruction of all the pre-Civil War regalia in 1649-50, carried out at the behest of Oliver Cromwell following the execution of King Charles I (many of the earlier crown jewels, dating from the Anglo-Saxon period, had already been replaced in the early 13th century after items were lost while being taken across The Wash during the reign of King John in 1216).

Following Cromwell’s destruction, new regalia was made on the orders of King Charles II. Modelled on that of his father, it was used in the king’s coronation on 23rd April, 1661, and cost more than £12,000.

Today, St Edward’s Crown – with which the sovereign is crowned by the Archbishop of Canterbury – is the principal piece of the regalia. Other items include the Sovereign’s Sceptre, topped with 530 carat First Star of Africa – the largest flawless cut diamond in the world, Queen Victoria’s small diamond crown, and the Imperial Crown of India. There is also a crown made for Queen Elizabeth, the Queen Mother, for her 1937 coronation which features the famous Koh-i-Nur (‘Mountain of Light’) diamond.

Until 1303, the Crown Jewels had been housed at Westminster Abbey. Following a successful robbery that year, however (after which most items were recovered), they were moved to the Tower.

The most famous attempt to steal the Crown Jewels was made by an Irishman, Colonel Thomas Blood, in 1671. He and his gang had arranged to see the jewels (this could be done for a fee) but when they arrived, used a mallet to knock out the jewel keeper before stabbing him.

Colonel Blood had hidden King Charles II’s crown under his cloak, squashing its arches of in the process, while his companion Robert Perot had stuck the coronation orb down his breeches and Blood’s son was in the process of sawing the sceptre in half when the keeper’s son returned unexpectedly and raised the alarm.

Arrested, Blood got off rather lightly – King Charles II decided, apparently for some unknown reason, to pardon him. Security around the jewels, however, was tightened – iron bars were used instead of wooden ones and people were thenceforth forbidden from handling the jewels.

The Crown Jewels are now housed in the Jewel House at the Tower, built in 1967 in the west wing of the Waterloo Barracks, and guarded by the Yeomen Warders.

WHERE: Tower of London (nearest tube station Tower Hill); WHEN: 9am to 4.30pm, Tuesday to Saturday, 10am to 4.30pm Sunday to Monday (until 28th February); COST: £18.70 adults; £10.45 children under 15; £15.95 concessions; £51.70 for a family (prices, which include a voluntary donation, are valid until 28th February); WEBSITE: www.hrp.org.uk/toweroflondon/. For more on the Crown Jewels, see www.royal.gov.uk/MonarchUK/Symbols/TheCrownJewels.aspx or the Royal Collection website, http://bit.ly/i9FM3