If Britain lay one hundred miles farther west

What would change if the United Kingdom were one hundred miles farther west?

Britain would gain some air-defence depth and face a wider North Sea, while barriers and aircraft-range requirements would become more demanding.

The counterfactual changes distances more than it changes Britain's fundamental strategic position. A wider North Sea and the altered geometry of the Channel would make a First World War barrier somewhat harder to establish. In the Second World War, the added distance would improve air-defence depth but would also encourage longer-ranged British aircraft. Those aircraft could then prove more useful in the Mediterranean and Pacific theatres. Britain's changed position in the Gulf Stream might also affect its climate.