The Police during 'Training' often do more damage than trespasses do!
MoD Property depends on how active it is, and disused sites also get used for Police, Firearms, Drugs, Dogs & UKSF Training at times, but that alone does not make it an 'Active' site unless signs tell you otherwise.
Doesn't matter how 'busy' it is, it's whether it's one of these designated sites...
Protected sites
Royal, governmental and parliamentary sites:
85 Albert Embankment, London
Buckingham Palace, London
Ministry of Defence Main Building, Whitehall, London
Old War Office Building, Whitehall, London
St James’s Palace, Cleveland Row, London
Thames House, 11 and 12 Millbank, London
The Chequers estate, near Aylesbury, Buckinghamshire
10 - 12 Downing Street site as well as 70 Whitehall
Government Communication Headquarters (GCHQ), Harp Hill, Cheltenham
GCHQ, Hubble Road, Cheltenham
GCHQ, Racecourse Road, Scarborough, North Yorkshire
GCHQ, Woodford, Bude, Cornwall
Highgrove House, Doughton, Gloucestershire
Palace of Westminster and Portcullis House site, London
Sandringham House, Norfolk
Windsor Castle, Berkshire
Protected Ministry of Defence sites
HMNB Clyde
RNAD Coulport
Northwood Headquarters
RAF Flyingdales
RAF Menwith Hill
RAF Croughton
RAF Lakenheath
RAF Feltwell
RAF Mildenhall
RAF Brize Norton
SMC Marchwood
RAF Fairford
RAF Welford
Licence nuclear sites
Civil sites:
- Sellafield, Cumbria
- Dounreay, Scotland
- Capenhurst, near Chester
- Drigg, near Sellafield
- Harwell, near Oxford
- Springfields, near Preston
- Windscale, within Sellafield
- Winfrith, near Wool in Dorset
- GE Healthcare sites in Amersham and Cardiff
- London University’s Imperial College of Science and Technology site in Ascot, Berkshire
- Berkeley, near Bristol
- Scottish Universities Environmental Research Centre at Birniehill, East Kilbride
Nuclear power station sites:
- Chapelcross, Dumfriesshire
- Dungeness A and B, Kent
- Hartlepool, near Middlesborough
- Heysham 1 and 2, Lancashire
- Hinkley Point A and B, Somerset
- Hunterston A and B, Ayrshire
- Oldbury, near Bristol
- Sizewell A and B, Suffolk
- Torness, East Lothian
- Bradwell, Essex
- Calder Hall, within Sellafield
- Wylfa, on Anglesey
- Trawsfynydd, Dolgellau, Wales
Defence sites:
- Atomic Weapons Establishments sites near Aldermaston and Burghfield, Berkshire
- Devonshire Dock Complex, Barrow-in-Furness, Cumbria
- Devonport Royal Dockyard, Plymouth
- Rolls Royce Neptune site and Nuclear Fuel Production Plant in Derby
- Rosyth Dockyard, Fife
In summary, trespass on any of those and you'll get a proper shafting.