I'm going to summarise, because it's a very big subject...

Some economists like Acemoglu and Robinson would argue that conditions in Britain during the Renaissance were somewhat similar to those in Germany and North Italy, leading to the creation of institutions that focus on wealth creation, rather than wealth extraction. This would explain the fact that these three countries have the oldest universities in the world: wealth creation relies on a certain amount of education, you need a big class of well educated people to produce wealth.

Combine this general institutional set-up with a powerful navy, and a country that is ideally located to make full use of the seas for trading purposes (trading is much more cost effective by sea than by land), and you've got yourself a clear winner in a world that slowly shifted away from mercantilism towards free trade economics.

To add to what Jecter said, because I think he has it right, the British Navy coupled with Britain's status as an island nation of substantial size and without being too far removed for greater Europe, affored her a strategic advantage in both colonization and defense. As you can imagine, a strong and robust navy was paramount in building and sustaining distant overseas enterprises equally as much as it was for projecting hard power to deter competitor nations and, at times, political enemies from "moving in" on what was considered rightfully part of British claim. Congruent to this idea or perhaps in part what gave rise to it was that Britain, provided it had a formidable navy, had no real need to maintain standing armies in the Isles for anything outside of keeping domestic order or on the occasion that they might need to involve themselves in mainland European wars. This in stark contrast to the situation in Spain and France, for example, where the necessity for large standing armies or armies easily and quickly mustered was a crucial aspect in detering their enemies from doing anything rash, or on occasion as political chesspieces. The maintance and costs of these armies were no small matter, as one could guess, and keeping them in economically well developed territory rather than fighting to secure new avenues of profit gave them a rather poor return-on-investment. The British, on the other hand, had much more liberty, again because of their geography and navy and the protection it afforded them, to utilize their armies in a more cost effective way.