[1] The church stands within the extent of a recently discovered Roman fort[2] at the top of the hill overlooking the town.

There were presumably several later restorations, but in 1861 an architectural survey of the diocese of Exeter noted that the whole church is in a sad state, chocked with pews of all heights .

encumbered with hideous gallery and collection of rubbish within.This resulted in the thorough restoration of 1867, carried out at a cost of £600, and under the direction of Mr. James Piers St Aubyn (1815–95).

St. Aubyn, a relative of the well-known family residents of St Michael’s Mount, had an architectural practice in London and Devonport, and was responsible for the restoration of many West Country churches.

Here at Calstock the floor levels were altered, the existing tiles laid, the chancel given its present roof, and the building furnished with plain pitched-pine pews.

Pinnacles once surmounted the turrets, and according to the Exeter Mercury of 24 November 1790: "a storm of thunder and lightning happened ...

Inside the church, just north of the pulpit, are two plaques: Other gravestones record deaths from mining and other industrial accidents.

Though now set in quiet rural countryside, the church during the 19th century was surrounded by industrial activity, and the people of the parish were much involved in quarrying, brickmaking, lime burning and boat building, as well as copper mining.

Also in the graveyard is the gravestone of two Shadrak brothers who decided to emigrate to Canada in search of work after the collapse of the Tamar Valley Mine.