<<However, I do recall in the early eighties, some trials with 27L (or 28L, can't remember how long ago!) depart with 23 arrive. I don't think it was strictly LAHSO, but was done more on timing to avoid confliction.>>
23 against 28L departing was no problem, although that config was rarely used, and I don't recall any special procedures. 23(L) versus 28L landing was a radar controlled operation and there never was a laid down procedure for the use of both runways - just pure radar skill. If the wind on 23 dropped off the results could get exciting to say the least and a colleague faced with such a situation asked the 23 lander if he could land and hold short of 28L. For the 23 lander, being a clockwork mouse, it was no trouble and he cleared on the southern dual carriageway, miles before 28L. The pilot of the tiddler was mightily impressed with the "procedure" and wrote to the boss at Heathrow to offer thanks, etc. My colleague's feet never touched the floor as he was hauled downstairs to stand on the boss's bit of Axminster!!! We were emphatically instructed that LAHSO was not permitted!