Further information can be found at https://www.prisonhistory.org/lockup/mells-lock-up/
'Lock-up. C17. Doulting rubble, dressed quoins, pyramidal stone tile roof with circular stone capping. Small rectangular structure having central pointed arch door opening in block surround; studded vertical plank door with iron surround and strap hinges, small square peephole with hinged iron barred grille. Second inner door of similar style. An unusually complete survival.'
Historic England, National Heritage List for England, 'Lock-Up, Mells', LEN 1058320 (https://historicengland.org.uk/listing/the-list/list-entry/1058320)
'In 1728, The Court Leet of Mells, had presented 'Thomas Horner and the Rev. Mr Paget to erect a guard house and to put stocks and whipping post in good repair.' As a result, Horner, who was Lord of the Manor, and the Rector, had the Blind House erected fronting onto a piece of 'the Lord's waste.' Horner's ancestor was 'Little Jack Horner' of nursery rhyme fame.'
Roy's Blog, 'SOMERSET. Lock-ups at Kilmersdon, Kingsbury Episcopi and Mells.' (13 July 2013) (http://roys-roy.blogspot.com/2013/07/somerset-lock-ups-at-kilmersdon.html)
Leslie Brooke, Some West-Country Lock-Ups (Castle Cary, Fox Publications, 1985), pp. 13, 67 (sketch)
Roy's Blog, 'SOMERSET. Lock-ups at Kilmersdon, Kingsbury Episcopi and Mells.' (13 July 2013) http://roys-roy.blogspot.com/2013/07/somerset-lock-ups-at-kilmersdon.html
Historic England, National Heritage List for England, 'Lock-Up, Mells', LEN 1058320 https://historicengland.org.uk/listing/the-list/list-entry/1058320