Beyond Altnabreac's excellent golden rules
may I add a 5th:
5. Lack of other public transport options (substitutability).
In Middlewich's case, you'll need to be able to show why stopping more trains at Winsford and having better bus links to Middlewich (e.g. every 15 minutes) isn't a better (or at least more cost effective) solution to whatever public transport demand you identify. Google suggests that it's less than three miles, and this presumably was one of the reasons that Middlewich lost its station in the first place.
Middlewich was one of several lines that almost certainly suffered because the timetable was so pathetic and badly timed. In 1959, it had 4 trains each way, with one extra train on saturdays.
Northwich to Crewe dep 06:59; 08:30; 13:45(SO); 17:15 (SX) / 17:20 (SO) and 18:50 (SX) / 18:55 (SO). Dep. Middlewich 9 minutes later, and mostly taking 26 - 33 minutes between Northwich & Crewe.
Crewe to Northwich dep. 06:15; 07:35; 12:38 (SO); 16:36(SX) / 16:42 (SO) and 18:06. The earliet arrival in Manchester Central was 08:40, and involved a 37 min. connection at Northwich. The second service gave a 7 minute connection for Manchester, arriving at 09:08. The last possible departures from Manchester Central were at 17:38 (SX) or 18:00 (SO).
So, apart maybe for workers at Crewe Works, or at Northwich industry, the services were not very attractive - certainly not for office / shop workers in Manchester.
And, although it may have grown a bit in recent years, Middlewich probably needs a 20,000+ population to attract a viable rail service. It does not even have a very direct bus service to Northwich - all through buses run via Winsford town centre (Arriva Service 37A) and take 47 to 48 minutes. (By rail, Northwich is just over 5 miles from Middlewich.)