“Almost singlehandedly” is way off the mark. Welchman, Tutte - the place was filled with eccentric geniuses; it was the success of management as much as the individual that Bletchley saw so much success.
(“The story of Hut 6” is a good read on the subject. What comes across was that success was down to serendipity as well as hard work, and some remarkably enlightened leadership.)
It’s worth mentioning that German cryptologists had some considerable success cracking British codes as well, notably including the cyphers the Admiralty used to communicate with merchant ships in convoys during the first half of the war. This was a major factor behind Britain nearly losing the Battle of the Atlantic before they even had a chance to participate in the re-invasion of continental Europe in 1944.