Over a thousand years ago an embankment or causeway was made to carry the road from Maney to Sutton across the marshy valley, and 600 years ago this embankment, - now the Parade and Lower Parade - which formed the dam for the mill pool, was reinforced with stone. Material to make the causeway and stone for the dam was taken from the hillside between Mill Street and Trinity Hill, leaving a quarry with a steep face.

Between the top of this quarry and the churchyard was a strip of land running from Trinity Hill to Mill Street which Bishop Vesey acquired and where he established the Grammar School. The school was at the Mill Street end and the Schoolmaster’s house, an old stone building called Saint Mary Hall, was on Trinity Hill; the land between them was the schoolmaster’s garden. The school fell down in the 1720s, but the schoolmaster’s house survived until 1832, when the churchyard was extended over the house and garden.

This extension of the churchyard entailed the levelling up of the old schoolmaster’s garden using soil from the old churchyard and from excavations at Trinity Hill (which used to be much steeper). Massive stone retaining walls were built against the quarry face and on either side of Trinity Hill; the old wall of the schoolmaster’s garden was strengthened, and a new battlemented churchyard wall was built on top of that.

The results of this work can still be seen from the car park of the Baptist Church, with the old brick garden wall and its stone coping sandwiched between the stone retaining wall and the brick wall of the churchyard. More was visible in 1985 when the late Norman Evans was making his measurements of the features as part of his comprehensive (unpublished) history of the Parish Church. This was before the Trinity Centre was built, when the quarry face was less overgrown and more of the earliest feature, the old wall of the schoolmaster’s garden, could still be seen