Some events can't be held in London. Sailing for example.
nothing
There are 6 sports being staged out side of London, as you can see form the related link below.
There are a few venues that, by necessity, are outside the boundaries of Greater London, such as the Weymouth and Portland National Sailing Academy some 125 miles (200 km) southwest of London, which hosted the sailing events. The football tournament was staged at several grounds around the UK.
302 events
there are 32 events at the 2012 olympics.
There are 302 events in 26 sports for the 2012 London Olympics
302 events were held
Weymouth and Portland National Sailing Academy some 125 miles (200 km) southwest of London hosted the sailing events. The football tournament was staged at several grounds around the UK.
No they have 302 events
36
50
302