Great Western Coffee Shop

If I held an ENCTS bus pass ... how long would it take me to travel from Melksham starting at just after 09:30 to London?

I am thinking x72 to Devizes (I'll walk to Bowerhill to picket up at 09:31, arrive Devizes 09:43), 49 to Swindon (10:07 from Devizes, 11:05 in Swindon), S6 to Oxford (11:25 from Swindon, 12:47 in Oxford) - but then I am allowed onto the London direct service (13:00) as far as Lewknor (13:45). which otherwise seems only to have a daily bus called the RL30 ... how would I get from Oxford to the London 'burbs best?

Following up my own post (help!)
12:52 (Oxford) to 14:20 Henley (x49?)
14:31 (Henley) to 15:07 High Wycombe (800)
15:25 (High Wycombe) to 16:22 Slough (74)
16:33 (Slough) to 17:33 Hounslow (81)
17:40 (Hounslow) to 18:25 Shepherds Bush (273)
18:30 (Shepherd's Bush) to 18:55 Lancaster Gate (94 or 148)

So I make that 9 buses and 9 hours 24 minutes elapsed time.  Could I do better?

You had me scratching my head there. I don't know a 273 bus in Hounslow. I'm sure you mean the 237.

Silly me ... the 273 used to run from Easterton to Bath via Melksham and Kingsdown - twice a week.

From Oxford, X39/X40 to Reading, X4 to Bracknell, 703 to Slough, 702 to London is a possibility.

Ah - do Green Line coaches accept ENCTS passes?  I had perhaps guessed wrongly that they don't.

13:12 Oxford -> 14:40 Reading
14:50 Reading -> 15:54 Bracknell
16:03 Bracknell -> 17:06 Slough
17:35 Slough -> 18:43 Victoria

So actually my previous example Oxford - Henley - High Wycombe - Slough gets me there 16:22, then
16:35 Slough -> 17:43 so an hour saved by mixing the routes

Both 702 and 703 routes are standard all stop commercial routes, at least outside of London's boundary. I recall Dad doing the trip via Bracknell to London when he retired.