An interesting distinction is between secondary stations which serve trains also mostly heading to the largest station- Colchester, Cardiff, Exeter- and secondary stations where most trains don't also serve the main station- Glasgow, St Albans, Croydon, Birmingham. Quite a number of towns- Chesterfield, Leicester, Oxford, Reading from memory- had a secondary terminus of the latter sort, the Reading Southern reigon one having been built into the main station in the 1960s, and the Oxford gaining something similar with the Chiltern bay platforms which serve the same line as Rewley Road used to. Plenty of the latter would have ended up very basic terminals if they had survived!