Great Western Coffee Shop

This may have been dealt with last summer when the Cotswold Line was blocked for the redoubling work. Anyway, I plan to travel from Gt Malvern to Dorking on Sunday 28 February on the 1705 from Gt Malvern, which will be diverted via Cheltenham and Swindon. I'll be travelling with my Network Card beyond Worcester. Will I be OK to use it on this service? I won't be breaking my journey between Worcester and Reading. I don't really want to go to Hanborough, get on a bus and add an hour to my journey.

 I doubt anyone will argue whether officially valid or not

Hey FA, only problem I can see is whether an Evesham routed ticket would be allowed on the diverted service, as the route Evesham or Stroud is not available in conjunction with a Network Railcard. I would fire off an email to FGW and use words such as regular traveller, goodwill etc and print off any favourable response.
From my whistle-stop research you can get a NSE discount on the via Evesham, via NOT Birmingham and via Any Permitted, but not on the via Evesham or Stroud.
I would therefore imagine, as you're not breaking the journey, that a Not Birmingham ticket would be valid, even if an Evesham one was not.

What I fine - not just during the blockade but on similar services when engineering happens - if its even vaguely valid, no one on FGW questions it.  I went via NWP for the six weeks on a WOS-RDG ticket and only paying a lUD-HFD excess to cover the arriva section.    Was WOS-RDG via NWP valid - who knows - but I think it was only questioned once.

Well I wouldn't, when NXEC or GNER before them had engineering and weren't running passed Edinburgh, I would take 'Not Glasgow' tickets on my Queen Street's.
On the route you're on about it's for the most an FGW fare so I doubt there'll be too much of an issue.

As it's an officially arranged FGW diversion, like those last summer, then I'm sure the same ticket rules will apply, which was that via Evesham tickets were valid the long way round, including Network Railcard discounts.

The closure north of Oxford (looks like renewing points at Oxford North junction) applies next weekend Feb 20-21 and 27-28. Also means XC and FGW Banbury and Bicester Town services won't be running.

Thanks to those who offered comments and advice. FGW Customer Services have confirmed that so long as there is no break of journey 'off-route', then I will be able to use my Network Card for this diverted journey.