The small round tower at the western end of the site was probably built by John Blaker who lived at 7 Priory Crescent. He purchased the Priory site in 1855 and there is no mention of the tower in the sale particulars or on the sale plan. It is however shown on the 1873 Ordnance Survey map so presumably was built between these dates. Since he owned land on both sides of the railway line, he may have built the nearby tunnel under the tracks. The structure was likely to have been a prospect tower - a popular Victorian landscape feature.
Blaker, who became Town Clerk of the Borough of Lewes, was the son of a Lewes draper. In about 1830 he founded Blaker Son & Young the firm of solicitors practising at 211 High Street. His brother Edgar was also a partner. The Sussex Express recorded Blaker's death to have been on 8 April 1864 'after many years of severe suffering'. The note of probate describes him as 'gentleman' and states that his effects were valued at under £1,500.
In front of the tower is new seating for school parties visiting the Priory.
The Round Tower is included on the Statutory List of Buildings of Special Architectural or Historic Interest Grade II.