Reports on that train available
here, although I don't know how long that link will be active for.
Shown as departing Reading on time but also as cancelled at Reading. This may go back to something that was discussed a little while ago somewhere on the board, where the third-rail part of Reading station has a different location code from the main part of the station. So if the train departed from a different part of the station from the usual then it may be that it shows up as "cancelled" from the third-rail station even though it left from the main part, if you see what I mean.
Last report as I type this was 3 late Wokingham. I don't know how much jiggery-pokery is involved with routeing the train from platform 10 to the Guildford line, but it looks like this
may have happened from what I can decipher.