The 55-year-old's death is being treated as 'unexplained' by police.
Police say they want to trace a woman who may have more information about how the victim came to sustain his head injuries.
They also asked for people in the Prince of Wales Avenue and Oxford Road area between 02:00 and 02:30 BST on Sunday to come forward.
The woman sought by police is described as mixed-race, 5ft 2ins (1.57m) tall, aged around 35, and slim with long wavy black hair.

Scarr, 22, who starred in Stourbridge's run to this season's FA Cup third round, has signed on a two-and-a-half year contract, for an undisclosed fee.
He becomes the sixth signing made by Blues in the January transfer window.
On top of the pre-arranged completion of striker Lukas Jutkiewicz's move from Burnley, new boss Gianfranco Zola has now made five more signings.
As well as bringing back Craig Gardner from West Bromwich Albion, he last week signed Middlesbrough full-back Emilio Nsue, Cheick Keita from Italian Serie B club Virtus Entella, and winger Kerim Frei from Turkish side Besiktas.
Stourbridge boss Gary Hackett said: "We have agreed terms with Birmingham. We have accepted we won't have Dan with us moving forward and good luck to him. He deserves the opportunity."
Find all the latest football transfers on our dedicated page or visit our Premier League tracker here.

The company agreed to pay $835m (Â£602m) - less than the $1.06bn a court in Kansas ordered it to pay in 2013.
Dow was hoping the Supreme Court would overturn the ruling, but the death of Justice Scalia left it evenly spilt between conservatives and liberals.
A split decision in the Supreme Court reverts to the lower court's ruling.
In a statement Dow said it settled because of the "increased likelihood for unfavourable outcomes".
The company said it still believed the original verdict was "fundamentally flawed," but felt settling was in the best interest of shareholders.
Last year, Dow announced plans to merge with competitor DuPont in a $130bn deal.
A man has died in hospital after being found unconscious inside a property in Reading in the early hours of Sunday.
[NEXT_CONCEPT]
Championship side Birmingham City have signed defender Dan Scarr from non-league neighbours Stourbridge.
[NEXT_CONCEPT]
Dow Chemical agreed to settle a class action lawsuit after determining the death of Supreme Court Justice Antonin Scalia made victory less likely.