TOWN planners often catch it in the neck when they allow destruction of the old to be replaced by the new but there is sometimes an upside to the work of the wrecking balls, bulldozers and pneumatic drills.

Because it can offer archaeologists a chance to discover what was there a long time ago.

No-one is going to start excavating the foundations of a building while it’s still standing. But knock it down - different story.

That’s why, in many ways, James Dinn’s new book The Archaeology of Worcester in 20 Digs (Amberley Publishing £15.99) is one of the most interesting written about the city in recent times.

James, in case you don’t know, is Worcester’s archaeological officer so is ideally placed to be your guide through some of the most ground-breaking and unusual discoveries ever made by those uncovering the hidden architecture of the Faithful City.

Apart from an initial foray into the excavation of the huge mound that once stood just south of the cathedral and was the site of Worcester Castle, which was levelled and taken away in the 1830s, the other 19 digs are all within recent-ish memory.

They start with what James calls “Worcester’s first ‘modern’ excavation”, which was along Copenhagen Street leading down to Warmestry Slip on the Severn in the 1950s, and end in the development to create the new Cathedral Square in 2015.

Discussing the latter, he said: “The roundabout at the junction of College Street, Deansway and High Street was built in the late 1960s and was a key part of Worcester’s traffic system.

"However, a decade later High Street became pedestrianised making the roundabout a redundant eyesore.

"Yet, such is the persistence of these type of features in the urban landscape, it took 35 years to remove it!”

Cathedral Square lies at the very heart of Worcester, within the Roman defences and on the edge of the Anglo Saxon and medieval cathedral, and the dig was expected to have very high archaeological potential.

But it is also on the A44, one of the county’s busiest roads, so closing that while excavations took place was a non-starter.

Which meant people had to work surrounded by traffic. Literally on an island.

James added: “In the event, a combination of engineering and economic factors meant that relatively little of the site’s archaeological potential was realised by excavation and there was no opportunity to investigate the rare exposures of Roman remains in detail and they remain safely buried.”

However, many old cellars and artefacts were uncovered and he writes: “A very moving element of the project was the literal re-emergence of nearby Lich Street into public view. This medieval street was completely swept away in the 1960s to make way for the Lychgate shopping precinct.”

Naturally, the Lich Street dig itself, which took place over 1965-66, gets comprehensive coverage and although it has laboured ever since under the description 'The Sack of Worcester', a description coined by a national writer appalled by the destruction it brought to a historic, if largely slum, area of the city, the archaeological side of it was, well, groundbreaking.

James explained: “For the first time in Worcester, archaeology became the collaborative endeavour which will be familiar to anyone who has watched the Time Team programme on television or visited a modern excavation.

“As well as the volunteer diggers, Scouts were drafted in to wash finds. Leading archaeologist Philip Barker, a pioneer in modern excavation techniques who had come to live in Worcester, had contacts in the University of Birmingham and beyond which were invaluable when it came to specialist reports on subjects as diverse as soil bacteria from a cesspit, medieval leather shoes and some moss found packed into the pointed toe of one of the shoes.”

James' book covers all the main archaeological digs that have taken place in Worcester over the past half-century, including the construction of City Walls Road in the 1970s, the Blackfriars and Angel Place development of the 1980s and The Hive and the city university’s conversion of the former Worcester Royal Infirmary in the mid-2000s.

However, despite the enormous technical advances in equipment, it is somehow reassuring to discover there is sometimes no substitute for a person on their hands and knees with a trowel.

For when radar hinted at the presence of a hidden medieval sandstone gatehouse in the confines of the cathedral roundabout dig, the reality turned out to be a modern concrete manhole cover.