theageofthetra
On Moderation
In terms of platform numbers, the biggest stations closed were probably:
Blackpool Central
Glasgow St. Enoch
Nottingham Victoria
(10 or more platforms)
then
Birmingham Snow Hill
Manchester Central
(about 8 or 9 platforms)
followed by
Sheffield Victoria
Liverpool Central
Glasgow Buchanan Street
Edinburgh Princes Street
(5 or more platforms)
Cromer High, mentioned above, and closed long before Beeching. had 4 platforms, and was not very busy in later years.
What about Broad Street and Holborn Viaduct?