I LOVE those odd corners of London where, unexpectedly, in the midst of the modern, one stumbles suddenly on some living continuity with the distant past; the long, strange, hardy persistence of deep-rooted things in the city and the realm. The Royal Foundation of St Katharine, in Limehouse, returned in the last century to its old home in the East End, is one such place, and I was glad to be there for a few days, leading a retreat on poetry and prayer.

It was founded, astonishingly, in 1147, by Queen Matilda, who called it “my hospital next to the Tower of London” — a “hospital’ in the full medieval sense: a place of prayer with a chapel, a place of hospitality with hostel and almshouses, a place of healing, and, as time went by, and the trade along the Thames grew, a place of sanctuary for wanderers from many countries.

Over the mantelpiece is a 16th-century portrait of a former Master of St Katharine’s. His weathered, wise, and timeworn face gazes out at you from above a magnificent lace ruff and from beneath a ceremonial hat that looks strikingly like a child’s drawing of a crown. He could be one of the Magi from a Renaissance painting, but his name was Julius Caesar! He was, in fact, the son of an Italian immigrant who had made his way up the river, and, also, it would seem, up the strata and echelons of English society. St Katharine’s flourished under his stewardship, and he left his ladder there for others.

I felt his benign presence in the chapel, where his pulpit has been restored, and where I began the retreat with the poetry of his younger contemporary Shakespeare. Soon, we were crossing seamlessly back and forth between the centuries, reading sonnets on poetry and prayer, as though the compass-rose inlaid in the chapel floor, with its centre of rose-coloured granite from St Catherine’s Monastery on Mount Sinai, were magically transporting us in a time-ship, travelling, as the inscription round that compass says, “not by navigation but by Love”.

You carry that sense of time-slip, of the interplay between past and present, with you, even as you step beyond St Katharine’s walls. That evening, I wandered along by the pubs of Narrow Street, where The Grapes has stood these 500 years, leaning precariously out over the Thames, as Dickens said, “like a faint-hearted diver, who has paused so long on the brink that he will never go in at all”.

And when, having walked along by Regent’s Canal from Limehouse Basin to the Mile End Road, I stepped in to a little shop for coffee, my meditations on time were interrupted, or perhaps concluded, by a strange encounter. The shop seemed empty, but suddenly the door opened and a man strode in, took one look at me, and with a cry of recognition said: “You’re from the 16th century!” I was a little taken aback, but he would brook no denial. “You’re from centuries ago, I know you are. You’re a time-traveller, but you’re welcome.”

There was, it is true, more than a whiff of brandy on his breath, and perhaps it was my beard, my stick, my broad-brimmed hat, or his own inward agenda that gave this gentleman of the road such certainty. But, after we parted, with a chink of change, and I made my way down the darkening towpath, I began to wonder whether he might be right after all about the time travel, and whether I hadn’t better be hastening back to my chapel-TARDIS at St Katharine’s.