Not ever in the published plans. I’d recommend searching within this thread for the background, but there are numerous explanations of why the wires never went to Westbury, among them no suitable grid supply, and no suitable electric terminating services to use them.
I've just had a look on OpenStreetMap, and part of the 400kV transmission line from Bramley (Hants) to Melksham (Wilts) crosses the B&H at Beechingstoke (nr Patney & Chirton); there is also a 132kV(?) SSE transmission line from Andover to Melksham crossing the B&H just west of Urchfont.
A potential contender for SFC technology, perhaps?
Edit no. 1: it looks to me like the AT feeders west of West Ealing have gone live (i.e. Hayes SATS to West Ealing SATS). In this picture here (
https://flic.kr/p/2kY4Ct7), the blue earths previously attached to the headspan on the left are gone, with an orange (maintenance) earth in its place; in this picture (
https://flic.kr/p/2kYfuWT), taken 2 days afterwards, the orange earth has gone.
Edit no. 2:
https://www.networkrail.co.uk/running-the-railway/our-routes/western/oxfordshire/ shows a video of the planned Oxford Corridor Phase 2 works. On the video, at 22:24 minutes in, a CIG rendering of Oxford's new platform is shown, along with OLE over P3, P4 & the through lines. It does however stipulate that "electrification shown in this image will not be delivered as part of this project", although at around 40 minutes in, there is another passage on electrification, stating "The Oxford Phase 2 Scheme is futureproofed for electrification of the railway, which will bring cleaner, quieter trains.
Electrification remains a regional priority." (I put the important part in bold)