A group of astronomers from the north of England, which included William Gascoigne, formed around them and were Britain's first followers of the astronomy of Johannes Kepler.

"Nos Keplari" as the group called themselves, were distinguished as being the first people to gain a realistic notion of the size of the Solar System.

The two correspondents both recorded the event in their own homes and it is not known whether they ever met in person, but Crabtree's calculations were crucial in allowing Horrocks to estimate the size of Venus and the distance from the Earth to the Sun.

Crabtree made his will on 19 July 1644, and was buried within the precincts of the Manchester Collegiate Church on 1 August 1644, close to where he had received his education.

[7] A commemorative plaque was unveiled a few yards away in December 2005, at Ivy Cottage 388-90 Lower Broughton Road, which is thought most likely to have been the home of Crabtree and his family at the time when he was collaborating with Horrocks.