It's often claimed that you would be able to see the English Channel from the top of the Shard in London.
For a start all of Greater London will be visible and one will be able to see a number of British towns and cities from it including a distance of a record 72 miles to Southampton. Brighton and Canterbury to the south and Windsor Castle and Croydon are also expected to be visable in good clear conditions.
Lying to the north you'll be able to see to Cambridge and Colchester whilst the most westerly view will be Newbury and to the east Herne Bay giving you views of the Thames Estuary. The total area that is viewable is marked in green on the image.

Unfortunately, due to the lay of the land the Channel is not likely to be visible. A shame, but im sure the view will still be one to die for.
I beg to differ that Brighton will be visible from the top of the Shard. The South Downs run very close to the north of Brighton and wikipedia states that Ditchling Beacon (6 miles directly north of Brighton Pier) is 248m (814ft) in height. The distance from Brighton Pier to the Shard in a straight line is 47 miles and the top of the Shard will stand at 310m (1016ft). Now I wasn't the best at trigonometry back in school but I don't think I'll be having to get my protractor out to prove that these sums don't add up.
Anyway, if you could see through the South Downs and on to Brighton, then surely you would be able to see the English Channel? Brighton Pier sticks out in to it.
This just sounds like a white lie by the developers marketing team...