The services on this line were, up to closure, in a triangle Wrexham-Chester Northgate-New Brighton-Wrexham.
Being local at the time, and making use of it, of the three arms I would say the Chester arm was the most used of the three, measured by actual passengers rather than train frequency. The only physical closure was Chester Northgate station itself. After this the line, along with the CLC line in from Northwich, continued in use by substantial freight to the Shotton steelworks and elsewhere. I recall thinking at the time, and on to now, that some regrading at Chester over railway-owned spare ground would have allowed the service to be diverted into the main Chester General station. The two otherwise separate routes are very close - the North Wales main line passed physically under the Northgate platforms in a tunnel, and the CLC trains from there to Manchester were readily visible from the west end of the General station.
Most passengers were from the intermediate stations (as is still the case on the Borderlands line); I suspect someone from 222 Marylebone Road thought there was a duplicate Wrexham-Chester-Birkenhead route, so that will suffice.