just check the times for trains from Melksham on Good Friday ( Bank Holiday) and it seems we have trains as follows:
10:30 to Chippenham & Swindon
11:36 to Trowbridge & Wesbury
18:15 to Chippenham & Swindon
19:11 to Trowbridge & Wesbury.
The only service showing in Timetable "E" is the 19:11
Oh well we could go up to Chippenham for an hour on 10:30
