Working alongside architect John Wood, the Elder, the stone Allen mined was heavily used in construction work for development works in Bath. However, the mines did not consistently make a profit and he subsidised them from his postal profits.

After his death, he was buried in a pyramid-topped tomb in Claverton, Somerset. Allen is commemorated in the names of streets and schools in the city of Bath and was the model for the character of Squire Allworthy