This is going to get even more nerdy.
Further research leads to their being possibly Russula nana which used to be thought a sub-species of R emetica but was given separate species status in 1936. R nana is a sub-arctic species of moors and high ground so that fits the bill of the 900m altitude where you found them. However, R nana does not appear in the species record for the Drumochter hills, but that doesn't mean they are not there, just not in the record. R nana as the name implies are smaller. Attach a photo for your consideration.
Your specimens look to be going over (ageing) so would have bleached and started to fall apart.
Hope this helps and is at least mildly interesting.
PS - The Russians used to eat the bloody things (R emetica that is), not raw though.