The Guyson E12 was a run of two cars commissioned by hill-climb champion Jim Thomson and built by William Towns.

The first model was completed for Thomson in 1974, with Towns subsequently converting his own E-Type.

The E12 features a fiberglass body that attaches mostly to the existing superstructure of the E-Type, secured with screws and resin.

[2] The first E12 built, owned by Jim Thomson, features an upgraded version of the standard Jaguar V12 engine tuned by Ron Beatty to produce 345 bhp (257 kW) (for reference, the standard engine in the E-Type produces 251 bhp (187 kW)) through the help of six 44mm Weber LDF carburetors.

The second E12 built, owned by Towns himself, did not feature the upgrade as he thought it would spoil the looks of the car.