A series of drone photographs have revealed the extent of damage to an old hospital that went up in flames in a suspected arson attack.

More than 42 firefighters were called to tackle a large blaze at the derelict St Andrew's Hospital building in Broadland Business Park at around 5am on Thursday.

Norwich Evening News: Drone photographs have revealed the extent of fire damage to St Andrew's HospitalDrone photographs have revealed the extent of fire damage to St Andrew's Hospital (Image: Shaun Button, Drone Vision Norfolk)

Norwich Evening News: St Andrew's Asylum is said to be one of the earliest of its kind, dating back to the Victorian eraSt Andrew's Asylum is said to be one of the earliest of its kind, dating back to the Victorian era (Image: Shaun Button/Drone Vision Norfolk)

The site has become known locally as a break-in hotspot and explored by interested photographers and videographers who have shared images online.

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Police have since treated the incident as arson which Thorpe St Andrew councillor Ian Mackie said follows a "familiar pattern". 

Norwich Evening News: Extra buildings were added to the asylum in 1876 costing a total of £33,920Extra buildings were added to the asylum in 1876 costing a total of £33,920 (Image: Shaun Button/Drone Vision Norfolk)

Norwich Evening News: 250 more patients could be accommodated as a result250 more patients could be accommodated as a result (Image: Shaun Button/Drone Vision Norfolk)

"This is another fine and historic building lost, having already been heavily damaged over many years of neglect," he added. 

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It comes as the latest in a string of similar incidents in Thorpe in recent years, including at Pinebanks, the former Oasis centre, the Griffin pub and Thorpe Prep School.

Norwich Evening News: During its working history, the asylum went under a number of different names During its working history, the asylum went under a number of different names (Image: Shaun Button/Drone Vision Norfolk)

Norwich Evening News: It was known as Norfolk County Asylum, Norfolk War Hospital, Norfolk Mental Hospital and St Andrew‘s HospitalIt was known as Norfolk County Asylum, Norfolk War Hospital, Norfolk Mental Hospital and St Andrew‘s Hospital (Image: Shaun Button/Drone Vision Norfolk)

The blaze has sparked further questions about the security of such derelict sites, with the former hospital site having been out of operation since 1998 and planning permission for a business park in 2016 not being brought to life.

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However, a spokesman for the Lind Trust, which had previously been given the outline planning permission, insists the organisation is as frustrated as everyone about trespassing.

Norwich Evening News: The south side of the site was developed into housing earlier this centuryThe south side of the site was developed into housing earlier this century (Image: Shaun Button/Drone Vision Norfolk)

Norwich Evening News: The remaining buildings are grade II listed with Heritage EnglandThe remaining buildings are grade II listed with Heritage England (Image: Shaun Button/Drone Vision Norfolk)

They said: "The site is very secure, it has fencing welded together to make it very durable and it is checked weekly, and subsequently it is re-boarded weekly.  

"It is broken into almost every week, unfortunately – it is a never-ending job."