The two biggest league grounds Notts have played in

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at a guess , as the record was held for decades my first guess would be
Manchester City Maine road , 1934 fa cup replay v Aston Villa ( some books Quote Stoke) crammed about 84,000 in. the capacity was est to be around 88,000
and My best Mates uncle Bob Marshall from Hucknall played in that game, as he he did in 1933 and 1934 when man city won the cup at the
Old Wembley Stadium 1923 FA cup Final, inc Bolton Wanders had 123000 in.
plus Notts used to play Scottish teams before 1888 so if they played Queens park Its going to be That Big un in Glasgow.
they also played Barcelona away prior to the first world war, friendly we won 13-2 but i dont think their ground was as massive as it is nowadays.

if those three dont Qualify then its going to be Villa Park, or Charltons ground