Directly after the sentence you're quoting mentions that "as regards Yugoslavia and Czechoslovakia, . . . hope that sympathetic considerations will be given to some revisions of the Trianon frontiers." Ofc, who knows how "sympathetic" Yugo and CS is going to be to a nation who annexed their territories but I was simply speculating that these two government in exiles wouldn't have as much influence as Britain on the peace table, so I could imagine that Britain forces their hand to revise their borders to prevent future conflict.Okay, maybe I'm reading it wrong, but I don't see anything in the quoted image to even remotely suggest the British were considering letting Hungary keep territories acquired from Slovakia and Yugoslavia.
The quoted image says the Foreign Office (that is the British foreign office) did up a paper which explicitly is quoted as saying that as a defeated enemy state Hungary has no special considerations in regards to her future frontier particularly with regards to the British allies of Czechoslovakia and Yugoslavia, but that this does not necessarily hold with regards to Romania as another defeated enemy state. It later states that the British Foreign Office's paper on the subject proposed the immediate return to Trianon borders for Hungary in relation to Czechoslovakia and Yugoslavia with the allusion that this would be disabuse the Hungarians of even the faintest ideas that special consideration would be given to revision of the Trianon frontiers.
The only possible non-Trianon boundaries envisioned are clearly only with Romania.