This is a curious design for several reasons, especially if it is related to Armstrong Whitworth.
Firstly, there appears to be no spare A.W. designation, or existing description of one that matches this design. It could be that this design was a speculative un-tendered design.
Second the date of the design. The reference to a "Whittle engine" places the design to around 1941 at the earliest and probably no later than 1943. The reference to 40,000ft would indicate performance approximating F.4/40 for the Welkin, but of course turbojet power was not part of this specification. All the designs tendered, that we know of, were twin-engined aircraft with Merlins except for the Hawker P.1004 with a single Napier Sabre. Therefore a single Merlin would seem underpowered to meet the stated altitude. Furthermore most of those designs were two-seaters. The small cockpit windows seem to indicate a pressure cabin. It seems more likely that the intended jet-powered example without the interim Merlin may have been designed around F.9/40 or perhaps a speculative design pitched to the MAP, much like the DH.99 of 1941 or Hawker's P.1101 around the same time.
The other point is that by 1942 AWA were pushing ahead with flying wings and laminar flow wings, with John Lloyd very much in favour of low-drag wings. So much so that he put them on the A.W.49 ground attack aircraft of 1942. The A.W.42 was of pusher configuration too, but was a fairly conventional twin-boom design. I would seem logical that had this design been formulated in 1942 that a laminar flow wing would have been used. As to the tail arrangement, it is possible the tail-forward layout was chosen over the traditional twin-boom due to jet efflux concerns. Even so it seems a rather crude design overall, even compared with the workmanlike A.W.49.
As a jet-powered design the layout makes more sense for 1941 when designers were trying to come to terms with the new form of propulsion and designing for the altitudes it could reach. If this was a 1941 design it would also explain the lack of laminar flow or other tailless features that AWA readily adopted just a year later. It does rather make the interim Merlin-powered design shown here an oddity, certainly Gloster, de Havilland and Hawker didn't bother with piston-engined variants of their jet fighters, they were prepared to wait until an engine was ready. And there is no way a single Merlin could offer comparable performance over current fighters and certainly not at 40,000ft.