IAN COLLINS From pilgrim hospitals and crusader castles to the badges and bandages of the St John Ambulance charity, Ian Collins looks at a museum to good works flowing from a less than saintly history.

IAN COLLINS

When you come out of Liverpool Street Station the first image is of 21st century glass and steel - for the square mile of the City of London may now be Britain's biggest building site.

But between the construction sites there are glimpses of the capital as it has struggled and flourished over two millenniums.

Here and there are fragments of the Roman city wall, often set as the foundations to medieval bricks. Ironically, this perspective on antiquity was aided by all the devastation of the Blitz as, doubtless, by the Great Fire of 1666.

Let's look more closely at the fascinating district of Clerkenwell - where the last of the clockmakers and menders was wound down this summer to make way for the chic redevelopments of loft apartments and lofty shops, bars and restaurants.

Everywhere in this area you will keep coming upon the name St John - linked to Street, Square, Lane and Gate - and conjuring up images of uniformed volunteers getting busy with the bandages and ever-ready to enact the recovery position and the kiss-of-life.

The museum of our premier first aid outfit is indeed to be found in these parts. The address is Museum of the Order of St John, St John Ambulance, St John's Gate, St John's Lane...

You get the picture. Only, what is all this John business? And why is it so saintly?

The story is absorbing - and astonishing.

Medieval Clerkenwell was dominated by the buildings of rich religious orders. Lovely Charterhouse Square once served as a strict Carthusian monastery. The site of St James's parish church was home to the nuns of St Mary's.

And sprawling on a 10-acre plot around present-day St John's Square was the Priory of the Order of St John of Jerusalem.

The remnants of the palatial priory can still be seen in the Tudor gatehouse at the end of St John's Lane (now housing the museum). It's often mistaken for part of the city wall.

Traces also survive in the crypt of the initially round-naved priory church of St John, Clerkenwell, built around 1145, soon after the order - also known as the Knights Hospitallers - settled here.

Founded in the 1080s to run a hospital for sick pilgrims visiting Jerusalem, the order developed over the ensuing decades into fighters as well as nurses - shadowing the Knights Templars with a network of castles all over the Holy Land and defending the conquered Crusader States.

Once the last Christian stronghold of Acre fell to Muslim forces in 1291, the Order of St John held out in a series of island states such as Rhodes and Malta. Hence the alternative title of the Knights of Malta.

Clerkenwell was the administrative HQ of the enterprise, sorting the funding of those hospitals and castles with the profits from estates across England and sending a steady flow of men and money abroad.

Deputy museum curator Cressida Finch says that a report of 1338 listed the priory inhabitants as the prior and three chaplains of the order “plus 15 other chaplains and deacons. There was also a brother Knight, a keeper of the keys and a chaplain who served as a parish priest for the community.

“Others living and working in the community were a cook, chamber servants, people working in the dispensary, a janitor, two millers, a slaughterer, a brewer, a pig-keeper, a laundress, an attorney, clerks and the procurator-general and his staff.

“Paying guests (and their servants) and members of the order passing through on business were also recorded. In addition, members of the royal family and the nobility had the right to billet themselves on the priory.”

Phew. All that must have cost a fortune to maintain, and comprised a very taxing burden. Small wonder that in 1381 Wat Tyler's revolting peasants burned the priory and beheaded the prior on Tower Hill.

By the early 16th century the establishment had been revived and extended, an inventory listing the buildings as a great hall, counting-house, armoury, priests' and yeomen dormitories, wardrobe, prior's chamber, parlour, keeper's chamber, distillery and brewery, kitchen, stores, gatehouse and remodelled church with three attached chapels.

North of the gatehouse was an outer precinct with two courts and gardens, woodyard, slaughter house, laundry and porter's gardens.

And then, in 1540, the prior received a communication that caused him to have a fatal heart attack. The Order of St John was to be dissolved and the priory abandoned following Henry VIII's break with Rome.

Many knights fled abroad, some of those remaining were killed - adjoining Smithfield had been an execution site for centuries, being even handier than the Tower.

Whereas other religious houses' lands were stripped and ruined, the fine and centrally-located buildings of Clerkenwell were too good to lay waste. Henry used them variously as a store for “tents and toils for hunting and for war” and a home for his Catholic daughter, Mary. Under the rule of her half-brother, Edward VI, the bulk was blown up to provide stone for the palace of Protector Somerset.

When Mary came to the throne (ordering new executions in Smithfield) she invited the knights back in, before her sister, Elizabeth, booted them out again.

Not without a sense of humour, Gloriana then gave the priory church to her Master of Revels, for the plotting of court entertainments - feasts, pageants, masques and plays. No fewer than 30 Shakespeare plays were licensed here.

In its new guise as a Presbyterian meeting house, it was sacked by Londoners in 1710 in protest at Dr Sacheverell's impeachment for preaching against the Whigs.

Restored and enlarged as a second parish church for Clerkenwell, it was handed (back) in 1931 to an order which had been revived a century earlier as the Protestant Most Venerable Order of the Hospital of St John of Jerusalem (as distinct from the old Maltese branch which, ousted by Napoleon, was now based in Rome).

The order had already acquired the gatehouse, evicting what had become The Old Jerusalem Tavern.

Reviving nursing traditions, the St John Ambulance was founded here together with an eye hospital in Jerusalem.

Today, alongside the gatehouse museum, a converted house acts as administrative centre for a charity whose 45,000 volunteers devote four million hours a year to first aid and medical support services, community work and education, training and personal development for young people.

t The Museum of the Order of St John (020 7324 4070; www.sja.org.uk/museum) is open Monday to Friday, 10am to 5pm, and Saturday, 10am to 4pm. Tours of gate and church Tuesday, Friday and Saturday, 11am and 2.30pm. Free admission to the galleries, but donations requested for tours (adult £5, concession £4).