Phew - all is revealed in another swift search in the Newspaper Archive, saving me a lot of time and dead-end research!
I knew I was right to feel cautious about this, mainly because it was drawn from newspaper accounts with no primary source corroboration, and because it was very odd that there was no reference to it elsewhere in his career documentation or in the medal roll - even allowing for some gaps to exist there.
The Pall Mall Gazette, 13 November 1899:
'We are informed that the initials of Major Gale, R.E., wounded at Ladysmith on November 9 are H.R., and not W.A. (Walter Andrew), as we gave them on Friday. We regret the error, the responsibility for which, however, is not ours. The War Office returned the officer as 'Major Gale, R.E.', and a reference to the Army List gave the officer we described. As a matter of fact, the officer wounded had only the rank of captain in the List, though he is holding the local rank of Major.'
So there it is. Having researched H.R. Gale in the process (also of interest to me genealogically, as a cousin of my ancestor), there is nothing anywhere - including his WO25 service record - to indicate that he held the local rank of Major at this point (his promotion a year later was as Brevet Major), so I think I can be excused for discounting him on that basis.
However, a few days ago I began to feel uncertainty when I saw that H.R. Gale was one of the RE officers who had carried out a map-making survey in the Ladysmith area several years before the outbreak of war; one account said that the officers involved were 'caught up' in Ladysmith at the outbreak of war, so unavailable to General Buller for consultation. It would appear that this was indeed the case. Within a matter of days of his wounding (which cannot have been that severe, happily), H.R. Gale was with Buller's force and at Belmont, as shown by his medal clasp entitlement. He received eight clasps, and another factor which initially turned me against identifying him as 'Major Gale' was that these did not include the Defence or Relief of Ladysmith. It is still a bit difficult to understand, as he would have been entitled to wear another clasp, up to the maximum of nine. (Perhaps if he was trapped in Ladysmith but quickly escaped as a result of being taken out to the field hospital then he did not consider himself to be part of the defence force?)
This has been an interesting exercise. On now to research my other two ABW family veterans, both of whom are definitely there on the QSA rolls, a great-grandfather in the Shropshire Yeomanry and a gr gr uncle who was a Captain in the 9th Lancers. More on those in separate threads as I find out about them and hopefully don't encounter anything like the murky waters I've swum through here!
Many thanks to those who replied for their help in trying to solve this.