Lizard Point is the most southerly point in Great Britain at Latitude 50 degrees north and 5 degrees west.

Travelling due west from Lizard Point the next landfall is Newfoundland over 2200 miles away. The 50th parallel continues through Medicine Hat and Vancouver Island in Canada before crossing the Bering Sea to Russia, Mongolia, Ukraine and on through Europe to Normandy, France to complete the circle at Lizard Point. Travelling south the next landfall is 450 miles away near Santander in Northern Spain

The Lizard peninsula was made famous by Marconi in 1901 when he sent the first transatlantic wireless message to St John's Newfoundland and 61 years later in 1962 Goonhilly Satellite Earth Station became the link with Telstar to transmit TV and radio broadcasts from America to Great Britain and Europe.

Wrong answers are Portsmouth, Portland and Boston which are on the U.S. eastern seaboard and share the same name as towns and cities Great Britain.

More Info: en.wikipedia.org