T.F from Hellifield meaning on WTT

[Aire Head]

I have been researching for the timetable for my current project set on the Aire Valley Line in the 1950s.

 

I have been able to find the 1948 goods WTT which has proved to be very useful showing the variety and frequency of good traffic for my chosen model.

 

 

Largely I have found the information present to be self explanatory however the phrase shown on the above excerpt escapes me.

 

I can understand that it refers to a Mineral Train from Heysham to Doncaster which departed at 17:12 but the meaning of the bracketed letters I cannot.

 

It is listed as being double headed when it arrives at Skipton if that proves relevant.

 

Thank you for any information in advance.

[Aire Head]

Of course I’ve now just realised it could mean “Through Freight from Hellifield”