I have a copy of the F&MWTC compilation 1966 - 1988 ish, I can't remember off the top of my head (I'm at work) and when you read the old rescues the further you go back, the more common it appears to be, obviously in days before the collar it was more prevalent, although I remember the days of no collars and we only ever used two terriers in extremely big rock piles, such as Farrars or the Big House, for anyone who can remember and never in an earth, unless we needed to use another dog for a mark, but some of the rescues in the old year books state two, three or four dogs in drains!!! now