There used to be through carriages from London Euston to Southport, detached from the main London-Liverpool train at Edge Hill, and worked round to Southport avoiding the terminus at Lime Street.
In the same way, there used to be through carriages from London Kings Cross to Bradford Exchange, worked-round to Bradford via Ardsley and Morley High, and avoiding the terminus at Leeds Central.
These were detached/attached at Wakefield Westgate.