The fuselage was based on that of the T.29 Motor Tutor, increased in length and widened slightly; the wings and tail were unchanged.

It also found a market with civilian clubs in the UK, although most of these were built from kits and spares, using existing Tutor wings.

[1] The T.35 Austral was a one-off development with span increased to 15.64 m (51 ft 3¾ in),[2] sold to the Waikerie Gliding Club in Australia in 1952 After the RAF Cadet TX.3s were replaced by GRP gliders in the mid-1980s, the fleet was sold off, but never gained the same popularity with civilian owners as the side-by-side T.21, being a cheaper glider designed for "circuits and bumps", and only marginally soarable.

Some were instead converted to simple ultra-light aircraft as Motor Cadets, with the front cockpit replaced by a Volkswagen or similar engine, and a three-point undercarriage.

RAF Manston History Museum has Slingsby Cadet TX.3 VM791 on display marked up as XA312 Data from Coates, Andrew.