It has come to light tonight that for anyone heading by train to Newbury (for Highclere) the cheapest option off peak is to split tickets-
An Off Peak Day Return Paddington to Newbury costs £47.60 per person before railcard discount.
But on split tickets-
buy Paddington to Theale Off Peak Day Return £29.40, Off Peak Day Return Theale to Newbury £7 return- Total £36.40, and stay on the train when it calls at Theale.
Note that you have to be on a stopping train not an express train (bound for Exeter, Taunton or Plymouth) to make that work.
In the peak an anytime day return is £80.10 before railcard discount- however you can bring this down to £40.90 return by using the slower Elizabeth Line as far as Reading, and splitting tickets as -
Anytime Return Paddington to Burnham £19.20
Anytime Return Burnham to Reading £12.00
either Anytime Single (before 9am) Reading to Newbury £12.70 or Off Peak £9.60, or 2 Off Peak Singles at £9.60 each
Total £40.60 or £43.70
There are sometimes other ways to do the split at Slough or Taplow.