The remains of five archbishops of Canterbury have been found buried next to Lambeth Palace.
The coffins were discovered during building work at the deconsecrated church of St Mary-at-Lambeth, which stands on the banks of the River Thames.
Builders are currently renovating the church, the current home of the Garden Museum, which stands opposite the Houses of Parliament.
Site manager Karl Pattern, who was part of the team which made the discovery, said: "It was a very interesting day.
"We were exposing the ground as part of the job and lifting the slabs... when we uncovered the entry of what looked like a tomb.
"We got a camera on the end of stick and discovered numerous coffins and one of them had a gold crown on it."
Garden Museum director Christopher Woodward said: "I came here thinking, 'oh this sounds like bad news', and - wow!
"It's the crown, it's the mitre of an archbishop gleaming there in the dark."
Experts have identified one of those buried there as Richard Bancroft, who served as Archbishop of Canterbury from 1604 to 1610 and oversaw the publication of a translation of the bible into English.
It later became known as the King James Bible.
Another, identified from a nameplate on top of the coffin, is John Moore, who was Archbishop of Canterbury from 1783 until 1805.
Experts are still working to establish who else may be buried in the crypt.
Speaking about the development, Mr Woodward said: "This is one of the most sacred and precious sites in London.
"This church had two lives - it was the parish church of Lambeth, this little village by the river. But it was also a kind of annex to Lambeth Palace itself.
"And over the centuries a significant number of the archbishops' households chose to worship here and to be buried here."
Chair of the London Heritage Lottery Fund Wesley Kerr described the discovery as "really astonishing".
"To know that possibly the person who commissioned the King James Bible is buried here is truly incredible and really adds to the texture of this project," he said.