All the people defending the Private Property rule may as well sell your kit as there is going to be very few places you can shoot in England ( I would think most of the UK is the same)
Private Property as in your house or a company building is fine, but if you allow and encourage the public to enter free then this should be classed as a public space and the rule should not apply IMHO
As an example the Lake District or Peak District would be out of bound to take photos, you may have the right to roam, but it is still private land, be that a Land owner or the National Trust, if they all join your no photography on private property campaign then we are all going to be buggered.
No going to shoot planes at the Mach Loop and London is a non-no as I'm sure you know that every bridge in the City of London is privately owned.
Examples of private land in the City of London include:
All the park and garden areas in the City,
City churches and their gardens,
Paternoster Square,
Barbican Centre and the Barbican Estate,
Smithfield Market,
Leadenhall Market,
Museum of London,
Broadgate Estate,
Network Rail Stations,
London Underground Stations,
New Street Square,
Aviva Square,
Inner and Middle Temple,
Forecourt areas and squares attached to buildings (such as St Pauls Cathedral, Aviva, etc.)
All the Bridges in the City (Tower Bridge, London Bridge, Southwark Bridge, Millennium Bridge and Blackfriars Bridge)