Attendances - Update
So looks like the 18,578 for Dulwich Hamlet V Barnet in the FA Amateur Cup held on 19th March 1938 at Champion Hill (old Stadium) is the highest (record) Dulwich Hamlet cup attendance/crowd at Champion Hill
And the highest (record) League game attendance 16,254 for Dulwich Hamlet V Nunhead on 10th October 1931 (note some reports state 20,000)
The old Champion Hill overall record attendance was 20,744 for Kingstonians V Stockton in the FA Cup final held on 8th April 1933
The highest post war league or cup game attendances I can presently find reference to is
12,241 V Walton & Hersham Surrey Cup 2nd round on Saturday 18th February 1950 at Champion Hill - However, a report of Dulwich Hamlet V West Auckland Town 4th round Amateur Cup (replay) 10th March 1956 had a crowd reported at both over 12,000 and Sports Express as 13,000
(New) Champion Hill record attendance presently stands at 3,301 V Carlisle United set on 8th November 2019
The long standing record attendance for the new ground was 1,835, Dulwich Hamlet v Southport (14th November 1998) in the FA Cup
and in the League 1,523, Dulwich Hamlet V AFC Wimbledon (January 21st 2005)
Until this record was smashed on non-league day 6th September 2014 when 2,856 attended the game against Hampton & Richmond Borough and in the same season V Maidstone United where attendance was recorded at 3,000
Presently, record League attendance for a League game is 3,243 V Billericay Town 30th March 2019
Not forgetting 3,321 for the Bostik League Premier Division Play off final Dulwich Hamlet V Hendon at KNK Tooting 7th May 2018 (also a KNK record attendance)
The largest attendance at a game involving Dulwich Hamlet was 33,000 for the Dulwich Hamlet (2) V Leyton (0) FA Amateur Cup Final played at Boleyn ground, West Ham held on 3rd April 1937 (beating 27,840 at Selhurst Park for Dulwich Hamlet V Kingstonians in the FA Cup Semi final in 1932)
Post war 27,000 at Stamford Bridge for the FA Amateur Cup Semi Final against Dulwich Hamlet v Corinthian Casuals 10th March 1956
* please note very vague attendance report - and happy for any updates or corrections