The first few big scientists like Copernicus, Tycho Brahe, Kepler, Galileo were not British. Then came Newton. And, since then, it seems that the British started dominating science.
What was the social and political reason for this change?
"Then comes Newton". You forget John Napier, a.k.a. Marvellous Merchiston, who invented logarithms and decimal representation of real numbers. He was a contemporary of Brahe, Galileo and Kepler. His inventions revolutionized mathematics and astronomy. And he was not alone: Henry Brigs was another British mathematician who cooperated with Napier. There is no doubt that their discovery was the greatest mathematical discovery of that time.
Before Newton, French physics was dominant. The medieval physicists before Galileo and Newton who made the biggest contributions to physics (e.g., Oresme and Buridan) were Parisian, although there there were British ones like Bradwardine.
On the relationship between French and English physics, see pp. 55ff. of Duhem's Aim & Structure of Physical Theory or his article "The English School and Physical Theory." This article discusses the transition of physics manuals before Newton, which focused more on Cartesian physics (with his vortex theory, etc.), to those that discussed Newtonian physics.
It's probably best not to see science and physics in nationalist terms. What's more important was the revival of science in the modern era in Europe. This was preceded by a renaissance in science in the Islamic world. In particular by Ibn Rushd (Averroes) and Ibn Sina (Avicenna) who wrote widely on the philosophy of Aristotle. There was in fact a movement called Averroism in Europe which persisted up until the sixteenth century which shows just how widespread their influence was (Averroes himself lived in the 12th C).
Whilst both Newton & Liebniz both discovered the calculus, it was only Newton that came up with a quantifiable theory of gravity. Before him, there was only a qualitative theory, for example Kepler noted the universality of gravitational attraction. As Newton was the first to come up with a quantified law of a physical force this helped propel physics into a newfounded maturity in Europe.
Whilst Einstein himself dated the scientific revolution from Galileo, it's clear from the book, The Forgotten Revolution by Russo, that the modern science owed a great deal from ancient science. This isn't often acknowledged in modern physics courses but I imagine this will change in the future as a more inclusive history of science is written.