‘In the shadow of a tall, nine-arched, red brick railway viaduct, a long, thin, green valley extends besides the River Darent in Kent,’ writes Peter Stanford in his new book If These Stones Could Talk.

He is describing the Pilgrims’ Way as it runs south from Dartford to Otford. Thomas Becket came this way in his last weeks before death and Henry VIII as a pilgrim in his earlier years.

Peter is here to find a vital church for his history of Christianity in Britain and Ireland through twenty buildings. In the Darent Valley it is not Eynsford church where the feud between archbishop and king began or even Lullingstone’s lovely ‘church on the lawn’.

It is the building disguised as Lullingstone’s Roman Villa. Appropriately the Pilgrims’ Way passes the door and you can stop to have your passport stamped.

But go deeper inside and you will find evidence of an early church which may have had worshippers in the 4th century. Here is a chapel or a purpose built house church making it the oldest known site of Christian worship in the UK.

The author takes a wider look at Canterbury Cathedral suggesting that it had important saints before Becket’s murder brought greater crowds.

But even more arresting is the chapter on St Martin’s Church at Canterbury. It said to pilgrims arriving at Santiago de Compostela that they should stay awhile to look round rather than just heading home at once.

So pilgrims arriving at Canterbury should stay to walk on for just half a mile up to St Martin’s which is Britain’s oldest church and one of huge resonance.

If These Stones Could Talk offers a sweep of history around interesting places with a handy timeline and good index.

If These Stones Could Talk: The History of Christianity in Britain and Ireland through Twenty Buildings by Peter Stanford (Hodder £20).