Immaterial. The Henley was underpowered in any role. It was made a target tug 'cause the RAF couldn't think of any other use for it where it could be even marginally safely used.
You can't turn a sow's ear into a silk purse.
Underpowered !!? How? Source?
According to Gouling & Moyes - RAF Bomber Command and its aircraft 1936-1940, p.27
"With a wing span of 47ft 10.25in and an overall length of 36ft, the prototype Hawker P.4/34 was not much larger than the Hurricane and had a top speed of 292 mph at 17,100ft. It had a range of 1,000 miles at aa cruising speed of 215mph at 15,000ft."
Of the two designs put forward the Air Ministry decided the the Hawker was the best, and ordered (as I said before) 350, curious that the ground breaking aircraft the Spitfire only got an order for 310!
According to Owen Thetford - Aircraft of the Royal Air Force since 1918, the Hurricane I with the same engine as the Henley, had a max speed of 316 mph, not a lot of difference, considering the Henley's empty weight was nearer the Hurricane's max.
Or, John Terraine in - The Right of the Line, p.144:
"Hindsight tells us also - though the Hornum raid had provided a strong enough hint - that this belief in the so-called "big bombers" was pathetically misplaced.The hard fact is that the Whitleys, the Hampdens and even the wellingtons were unsuitable both for the direct support role that the war required, and the strategic role that the Air Staff yearned for. Indeed, it could be said that what May 1940 showed was that the RAF itself itself was unsuited to the war that Britain was fighting: what was needed was not Whitleys and Hampdens, but twice as many Hurricanes and Spitfires and a good close-support bomber ( the Hawker Henley, first flight 1937 - might well have been the one). But the RAF had set its face too resolutely against the idea of all forms of cooperation;..."
Moreover according to Peter C Smith - Dive Bomber p.61:
"But it was all too late. The RAF, by rejecting a purpose-built dive bomber with the Henley, had committed itself to the rejection of true dive bombing and all else was compromise. The overwhelming power in the upper echelons of the heavy bomber lobby carried all other considerations before it, and by the eve of the war the equally negleted fighter arm was crying out for what space design and building capacity there was to make good its own deficiencies. There was no room, even if the Air Ministry had been willing, which was far from the case, to add a dive-bomber programme as well at this late stage. And so the ill conceived Battles went to their doom in low flying suicide en masse in those desparate hours during the Battle of France in May and June 1940. Years later Sholto Douglas admitted that the pre-war policy of the RAF had been wrong: '... it would have been so much better, if, some years earlier, we had developed a dive bomber along the lines of Ernst Udet's Stuka, instead of devoting so much of our resources to the design, development and the production of those wretched Battles.' "
So it wasn't the aircraft that was the 'sow's ear' it was RAF policy!