Kelston Knoll is a Grade II listed building on the National Heritage List for England, located in the parish of Kelston, a village near Bath, in Somerset, England. The house is made from ashlar stone, with a slate roof, and was built in the Italianate style. It was completed in 1835. In the 1840s the house was owned by William Tudor, a surgeon and the Mayor of Bath. One of only three extant twopenny Mulready stationery letters sent on 6 May 1840, introduced on that date along with the Penny Black, the world's first postage stamp, was sent to Tudor's daughter, Isabella, who lived at the house. The letter is now in the Bath Postal Museum. Tudor died at Kelston Knoll on 9 July 1845, aged 77. His wife Julia Purvis survived him, and died at Kelston Knoll on 9 August 1890, in her 93rd year.