Peregrine (Peregrine Falcon) Falco peregrinus
This species has recovered well following a massive decline in the 60s and 70s. Formerly only a scarce winter visitor to south-eastern counties of the UK, there are now several pairs breeding. Some of these have selected busy urban settings for their nest sites, including the centre of London. In most places in Norfolk it's still relatively rare to encounter one outside of the winter period but very recently they have started to breed even here - for example a pair are nesting on Norwich Cathedral in 2011.
The species is fairly common in parts of North America. Three races occur here, all different from European birds. In the photos below I think the ones in California are race anatum and the ones in Florida should be tundrius. There are no accepted records of these races in the UK (two previously accepted records were recently reviewed and rejected) but there is an intriguing report from near Norwich in 1986. This record allegedly involved an encounter with a falconer's trained bird - the story has it that the falconer's bird 'brought down' the North American Peregrine alive. Though the story sounds doubtful, the identification is certain, for the bird was carrying a metal leg ring which proved that it had been rung earlier in the same year in New Brunswick, Canada (British Birds 97:478-479).
The American race tundrius is rather similar to the Palaearctic race calidus, both breeding in the high north but strongly migratory and wintering much further south. Both of these forms seem to go by the names Tundra Peregrine or Arctic Peregrine. There has been a recent spate of claims of calidus in the UK including some in Norfolk.