van Emden, F.I.,, 1954
Diptera: Cyclorrhapha Calyptrata (I) Sect (a) Tachinidae and Calliphoridae
Classic old-style RES handbook dichotomous keys to the British species.
The Tachinidae key is widely regarded as one of the most difficult in the RES Handbooks. Most of the problem lies in the initial key to subfamilies; after that it's more straightforward. Belshaw's more recent key is much easier to use, but the present work remains useful for the figures of genitalia.
Calliphoridae (apart from Rhinophorinae - now Rhinophoridae) has been superseded by the two Faun. Ent. Scan. volumes
Can be downloaded from the Royal Entomological Society website.