I would assume and hope there are.
But are there enough to justifty this as a commercial service?
Beyond Mach, I could believe it is justified.
This is why I had assumed it was a positioning train.
If it has to make the journey anyway and has a crew on board, then why not allow passengers to use it if they want, however modest the number on board in the early stages of the journey? It's a few quid in the farebox - and how 'commercial' are any services on the Cambrian routes anyway, given the hefty subsidy that ATW gets?
There's nothing unusual about trains like this being opened up to passengers. There are a couple of examples on my doorstep on the Cotswold Line. The current 05.14 from Oxford to Worcester ran for some time as empty stock from Reading or Oxford to Moreton-in-Marsh, where it then entered passenger service, even though it was crewed throughout by a driver and guard.
And the 05.12 HST from Paddington to Moreton-in-Marsh, which started running in May to provide the 07.09 back to Paddington, replaced a working out to Charlbury which ran empty stock from London. It even connects very nicely with the first buses of the day from Moreton to Cheltenham and Stratford-upon-Avon - HST arrives 06.45, buses leave 06.55, so perfect for insomniac tourists on a day trip from London.
Getting back on topic, I was in Knighton on Friday afternoon and observed the arrival and departure of a well-loaded 153 on the 14.05 from Shrewsbury to Swansea - train was about 12 minutes late after being held outside Craven Arms station to allow a delayed northbound Marches train to call and make a connection. Ten or a dozen people got off at Knighton, with four boarding.
Does anyone know how the new HOWL services are getting on and/or loadings on the line generally? They don't seem to have got much of a mention, despite this thread's title, and the HOWLTA and Heart of Wales Line Forum websites have nothing to say on the subject.