I took the trouble to join this forum in view of some of the rather disparaging comments I read about Huddersfield from people who, in my view, simply don't know what they are talking about. I was born in Wakefield, but lived in Huddersfield for 30 years. I now reside in Lytham St Annes, so I am lucky to have access to the WCML at Preston, the UK's only truly world class rail service, apart from Eurostar. We will also shortly have the additional choice of Grand Central's new services from Blackpool to London.
The case for Huddersfield having a London service is very simple - passenger numbers dictate it. Here are the 2018/19 passenger stats for the main stations in Yorkshire:
1. Leeds - 30.84m
2. York - 9.99m
3. Sheffield - 9.91m
4. Huddersfield - 4.90m
5. Doncaster - 3.92m
More people used Huddersfield than Bradford Interchange and Bradford Forster Square combined (2.61m + 1.95m = 4.57m) and Wakefield Westgate and Kirkgate combined (2.47m + 0.52m = 2.99m).
Huddersfield passenger numbers also eclipse those of many towns/cities that are major destinations from London, such as Derby 3.90m, Northampton 3.3m, Lincoln 1.96m, Exeter 2.62m, Newport 2.85m and Swansea 2.20m.
According to some comments on here, Huddersfield is full of low paid, low skilled people. If that's the case, how come it generates so much passenger traffic? Furthermore, the current levels of traffic are constained by the limited track capacity in and out of the town. As has been rightly pointed out on here many times, there is very little or no capacity to increase services at present. That, of course, will change when the Westtown (Dewsbury) to Huddersfield is increased from two lines to four and is electrified all the way through to Leeds. That is definitely happening. These improvements can only grow Huddersfield traffic even further. Huddersfield is a very big commuter town for both Leeds and Manchester. There are a lot of big earners on the payroll of Leeds and Manchester companies, so their incomes won't be reflected in stats about wages in Huddersfield.
The big shame in my view is that the proposed Alliance Rail/GNWR (Grand Central) services to Euston down the WCML didn't materialise a few years ago. Blackpool is getting additional London trains that it doesn't really need from Grand Central, because it is well served by Avanti, who in my view are on a far higher level. There is huge potential for trains from Bradford, Halifax and Huddersfield to access the WCML at Stockport, via Stalybridge. The paths created from Blackpool could have been used for that. This route would give the opportunity for direct services to both Euston and Birmingham without the need to go via Leeds. Maybe that is an option that will be explored again in the future.