Builders renovating a museum found a hidden crypt. The crypt contained 30 lead coffins, indicating high status. They were stacked on top of each other Some have names on them. One had what initially appeared to be a gold crown on top of it, which turned out to be a bishop's mitre.
In order of their terms in office the remains of archbishops found include:
Richard Bancroft, in office 1604-10,
Thomas Tenison, 1695,1715
Matthew Hutton, 1757-1758
Thomas Secker, 1758-68 had his internal organs buried in the churchyard
John Moore, 1783-1805, and his wife;
Frederick Cornwallis, 1768-1783
another coffin contains the remains of an ecclesiastical court judge of the Archbishop of Canterbury, Dean of Arches, John Bettesworth, 1677-1751
The most important man in history listed above is archbishop Richard Bancroft,who served in office 1604-10, but most importantly was the chief overseer of the publication of the new
English translation of the King James Bible, a process which began in
1604 resulting in the publication in 1611.
The find stunned everyone. Nobody knew the crypt or coffins were there and assumed there was no crypt due to the high chance of lower levels flooding due to being close to the Thames.
Why are they all buried there? St. Mary's-at-Lambeth church was built near Westminster Abbey in the 11th century. It served as a parish church and an annex to the Palace, both located in Lambeth. Many archbishops worshiped there and chose to be buried there. The church was deconsecrated in 1972 to become the Garden Museum. It was closed in October 2015 for renovations and schedule to reopen this month. Rather than move the coffins, there were left in place and a glass panel is now in the floor so visitors can see the coffins.
See and read more about it here http://www.bbc.com/news/uk-39613462