Leaving the Lady Chapel and walking through the north transept, crossing and south transept, we now take the little gate up into Abbey House’s orchard. Turning sharply left, we approach a large green-painted hut with a slate roof. This is the ‘museum’, on the site of the Chapter House: the hut is a very early site museum, erected under St John Hope’s excavation to protect the graves within. As such, the structure is a registered Ancient Monument in its own right; it was extensively repaired and renovated by English Heritage in 2009, as the original had had no damp-proof course and was rotting from the bottom up, aided by vandals.

The original Chapter House was a little larger than the hut, measuring 40 feet by 24 foot six inches. It was Early English in style and probably built earlier than 1250-60. The groining and vaulting shafts (which have been called most elegant and slender) are later in style than the doorway and outer walls, and were perhaps built under Abbot Simon (1264-69). Some column bases, capitals, parts of shafts and ribs and springers have all been found. The shafts consisted of eight filleted three-quarter rounds clustered round a centre.  

Parts of the doorway still survive. It was a double portal (like that into the chapter house at Lichfield Cathedral) and heavily moulded, leading from the eastern ambulatory of the cloister. It was six feet wide, and its jamb shafts, consisting of four colonettes, had dogtooth running up between them. The north wall of the Chapter House has a blocked up doorway into the sacristy, with an iron door-hinge which was still embedded in the masonry in Victorian times.

The pier at the eastern end of the room is lower than the others: this may be accounted for by postulating that the space above the eastern bay was occupied, as at Easby, by a Muniment Room.

The Chapter House itself had two aisles, and two painted windows at its east end. The canons' seats were positioned round the sides on a stone basement; the prior’s, abbot’s and sub-prior’s seats were below the east end windows. There were two painted windows at the east end, and all the windows have been described as ‘conspicuous’. The room was whitewashed throughout.

The canons assembled here every day after Prime to hear a chapter of the canons' rule, to pray, to transact business, to confess sins, and be punished as necessary. They assembled again in the evening for a spiritual lecture before bed.