Police are appealing for witnesses to an incident of grevious bodily harm at the car park in High Street yesterday afternoon at about 4pm.
Two men became involved in a verbal altercation which then turned physical, during which one of the men was punched in the face, causing him to fall back and hit his head.
The 31-year-old man was taken to the Royal Berkshire Hospital where he remains in a serious but stable condition.
Police are appealing to anyone who saw the incident to contact the Thames Valley Police Enquiry Centre on 101 and quote 4412593/14.
Alternatively witnesses can call Crimestoppers anonymously on 0800 555111.