It was described as ancient in 1215 and was named after Thomas Becket - which suggests it may have been founded after 1173 when Becket was canonised. However it is possible it was only renamed in 1173 and that it was founded when St Mary Overie Priory was refounded in 1100 in Southwark.
It was a mixed order of Augustinian monks and nuns, dedicated to Thomas Becket. It provided shelter and treatment for the poor, sick, and homeless. In the fifteenth century Richard Whittington endowed a laying-in ward for unmarried mothers. The monastery was dissolved in the Reformation, but reopened in 1551 and rededicated to Thomas the Apostle. It was reopened by Edward VI and has remained open ever since.
At the end of the 17th century the hospital and church were largely rebuilt by Sir Robert Clayton, president of the hospital and a former Lord Mayor of London. He employed Thomas Cartwright as architect. It is one of London's most famous hospitals - associated with names such as Astley Cooper and William Cheselden and Florence Nightingale.
There are only a few surviving pieces of the old Hospital in St Thomas St, Southwark - the most exciting of which is the Old Operating Theatre now a Museum.