I've dug out the relevant file at Kew (AVIA 54-768) and while it provides a few answers it does at least give the background to this project.
As Apophenia highlights here (
http://www.secretprojects.co.uk/forum/index.php/topic,26602.msg272306.html#msg272306), Bevan Bros. built an Isacco rotating-wing parachute in 1947 and a couple of technicians there began working on small ramjets.
Capt. R.N. Liptrot who crops up in many a British aircraft project history, by 1947 had been appointed as DDRD. Helicopters.
He had harboured a desire to build a small helicopter based on the Rotorchute and he suggested the firm should submit a proposal for a ramjet-powered helicopter.
The company would develop the rotor which would be fitted to an Fa-330 or a Rotachute airframe following ground tests. The RAE felt the project was feasible but had doubts an inexperienced firm would be able to make early success and advised a step-by-step development programme.
Spec E.1/48 was issued in December 1947 to cover this work and contract 6/Acft/2079/CB.9(a) was awarded to Bevan Bros. Aeronautical Engineers Ltd., Rettendon Common, Chelmsford, Essex to develop the rotor. Liptrot felt the development would only cost £8,000. It was planned to issue a second contract for the actual helicopter.
Liptrot felt a two-blade rotor would work but the RAE felt a single blade or triple-blade would be better to reduce vibration. There were some worries over yaw control in the hover but it was thought a separate control system would not be required.
Steve Coates and Jean-Christophe Carbonel's 'Helicopters of the Third Reich' states two Fa-330 airframes were assigned to Bevan Bros. and serialled VX259 and VX266. Work continued during 1949, it seems at least low-speed tests on the ramjets were undertaken and a wind tunnel was built (completed?) but the project was cancelled on 24 Feb 1950. Another Fa-330 was assigned to Bevan Bros. on 18 April 1951 and was serialled VX850 but there the trail goes cold.
I think we can safely discount the De Havilland TK.10/TS.10 from this Spec. TK-designs were apprentice designs rather than proper projects and Bevan was intended as the sole firm to do the ramjet work.