I think you're referring to 2L2 bubble insulation which is different to the foil blanket insulation the OP was proposing.I found that I had the foil in the cavity of my 2002 Barratt home - only discovered when I had a loft conversion done.
Looked pathetic really, the builders at the time must have had a good deal on it, and believed it was better than rockwool.
Oh, bit of research shows that this was standard at the time:
"A 2002 house will already have some form of cavity insulation because the Buildings Regulations at the time required this. These requirements were always being upgraded. If it was a Barratt home for example, this could be as simple as as an air bubble silver foil wrap around the inner leaf. This was being done circa 1997 onwards. Others might have, say 35 mm Celotex. I recall this standard having been reached by 2003."
https://forums.moneysavingexpert.com/discussion/5750359/cavity-wall-insulation
There's a whole history of discussion (including on this forum) of the silver foil blanket insulation (that the OP is talking about) and that how it was originally tested and it being considered at the time acceptable to use it on it's own but after the testing methodology was proved to be fake it lead to these types of insulation's requiring an air cavity to be utilised either side and an additional layer of other insulation - hence it's use is now impracticable and not cost efficient.