I'm from Thrum, and I remember them building 'Buttonhole' as you call it when I was a kid.
At the railway end they diverted the brook while it was being constructed. (Rushey Mead as we know it today wasn't even there, and Watermead Park was just the local gravel pits.)
We used to explore the culvert at the roundabout at the end of Humberstone Lane.
I think they were gated years ago.
We also used to walk along a new sewer/water pipe when it was being laid, that is now under the grass verge all along the East side of Thurmaston bypass, and we explored the air raid shelters in the grounds of Thorn Lighting before urbecks was even invented. - Anyroad, I'm rambling...
Yours, an old git.
(PS: The Nick Catford reference made me chuckle...)