UPDATE.
Wiltshire Police have issued an update on the Wood Street assault.
A 25-year-old male from the Swindon area has been arrested on suspicion of causing grievous bodily harm with intent. He remains in custody at Gablecross Police Station, Swindon.
The 27-year-old victim remains in a critical condition in the John Radcliffe Hospital in Oxford having undergone a significant brain operation overnight.
Wiltshire Police Superintendent Gavin Williams said: “I would like to take this opportunity to thank the local community for their assistance in this investigation so far and for allowing Wiltshire Police officers the space and time to conduct a thorough search of the Wood Street area yesterday.
“We have a dedicated team of officers working on this case to ensure that it is progressed as quickly and efficiently as possible.”
Wiltshire Police would still like to hear from any witnesses to this incident which took place at approximately 4.40am on Monday 1st April 2013 outside The Kings Arms hotel on Wood Street, Old Town, Swindon.
The victim was discovered with serious head injuries lying on the street outside The Kings Arms.
He was taken to the Great Western Hospital before being transferred to the John Radcliffe Hospital in Oxford.
The victim was wearing a cream shirt, dark blue jeans and black leather shoes at the time of the incident.
Anyone with information is asked to contact Wiltshire Police on 101 or Crimestoppers on 0800 555 111 where information can be left anonymously.
Wiltshire Police Press Office.
Original story
As a result of a serious assault outside the Kings Arms – 20 Wood Street – overnight Wiltshire Police have sealed off Wood Street and all businesses are closed as of 17-30 hrs.
A statement from the Wiltshire force is below. 
Wiltshire Police is appealing for witnesses after a man was seriously assaulted in Swindon.
The incident took place at approximately 4.40am on Monday 1st April 2013 outside The Kings Arms hotel on Wood Street, Old Town, Swindon.
A 27-year-old local man was discovered with serious head injuries lying on the street outside The Kings Arms.
He was taken to the Great Western Hospital before being transferred to the John Radcliffe Hospital in Oxford where he remains in a critical condition.
The victim was wearing a cream shirt, dark blue jeans and black leather shoes at the time of the incident.
Wiltshire Police Superintendent Gavin Williams said: “I would like to reassure the local community that this is a rare occurrence in Swindon and that we have a dedicated team of officers working on this investigation.
“There will be a heightened police presence in the Old Town area throughout the next 24 hours as we continue to investigate this incident.
“I would like to take this opportunity to thank the local community for their understanding and co-operation in this matter.
“Violent public place crimes have dropped significantly in Swindon during the past year and I want to reiterate that Wiltshire remains one of the safest counties in the country.
“I would urge anyone with information on this incident to contact Wiltshire Police immediately – any information, no matter how big or small, might prove vital to this investigation.”
Wiltshire Police would like to hear from anyone who was in the Wood Street or High Street area of Old Town, Swindon, in the early hours of this morning between 4am and 5am.
Anyone with information on this assault is asked to contact Wiltshire Police immediately on 101 or Crimestoppers on 0800 555 111 where information can be left anonymously.
Wiltshire Police Press office.