Mark, I can’t speak about the London heathlands, however I can comment on the Melbourne Sandbelt.
Kingston Heath has acquired multiple properties on the perimeter of the course, which made sense from a boundary safety perspective. Since I first played there more than 20 years ago, holes 2,6,11,12,13 & 18 have new back tees, and there are possibly more holes that do (14 & 16?). The new tees in 2 & 13 could not have been added should boundaries not have been extended. The course still plays quite short for elite amateur competition, much less Tour pro events.
Yarra Yarra is hopelessly troubled by boundary issues.
Royal Melbourne has been stretched significantly. East and West. The Club purchased a property beyond the original course boundary, and in recent years has extended the 15th tee onto what was a neighbouring residential property as recently as 2015. Dr John Green’s residence was purchased, the old home demolished, and much of the block now serves as a safety buffer from errant long second shots into the second green in East.
Driving ranges at KH, Commonwealth, Metropolitan are all too small to function as they did 25 years ago, much less as they were intended at the time of design.
Several clubs have incurred significant cost in erecting safety fences and nets on their periphery. God knows what insurance premiums Woodlands deal with, due to balls going onto White Street off holes 1 & 2. Same with Victoria on holes 2 & 3.
The issue might be more significant than you think. And that’s to say nothing of a loss of strategic intent.
Matt