Looks like I need to leave for Taunton on Friday ahead of the time my FOSS^▸ (Freedom of Severn & Solent Rover) ticket starts.  Any time day single Trowbridge to Taunton, £16.80, not via Bristol - so valid on the 06:42 from Trowbridge, change at Westbury, arrive Taunton on 09:01.

Any time single MELKSHAM to Taunton, best walk up fair £46.80 ... on the same train, leaving Melksham 10 minutes earlier - at 06:32.  Why £30 more for the 10 minute ride from Melksham?

P.S. 07:54 / Trowbridge, 08:01 to 08:22 Westbury also £16.80, or £11.15 with a senior railcard. Add £2 for the 06:54 bus Melksham Market Place to Trinity Church Trowbridge (and it will cut down on the distance I have to walk to the starring point too)

I suspect it has something to do with Bristol PAYG^▸ (Pay as you go), despite none of the start/finish stations being in that zone. Introduction of the cards involved replacing existing single fares, just below the return fare, by new ones at half the return fare. That is roughly what has happened with the Trowbridge fare.

Quite why this has been done is not obvious: it might be preparing for an extension, or trying to smooth out some of the anomalies (well-known for introducing more of them), or something else. And they could have got it wrong, of course.

Bath->Taunton is the same £16.80 fare as from Trowbridge - maybe a better option? There's even a £14.50 Advance on offer.

It gets even odder - the A to Z on the platform at Melksham offers departures to Taunton via Westbury and via Chippenham.  Yep, that's different journeys to the ones the GWR^▸ (Great Western Railway) online booking engine gives you, and ones that it won't offer you, nor will it offer a fare.  But nothing on the A to Z via Trowbridge and Bristol. 

Not sure that we're talking big business here - less that 1 in 500 ticketed journeys from Melksham are to Taunton; whether that's because it's not a journey people want, it's too expensive, it's awkward with difficult connections, infrequent and long waits, or it's hard to find out about.