Remember they had India, Australia(A whole continent), New Zealand and Etc......... during this era. Decline came much later after this Victorian age.
The “sun never set” on the British Empire after England gained India and other colonies in the Far East, events subsequent to and believed to more than make up for Britain’s loss of its North American “possessions.” The most significant and abrupt decline occurred after WWII with the loss of India, Canada, New Zealand and Malaysia. Australia won its sovereignty in 1931 if memory serves. Definitely prior to WWII. The Empire apexed after the Revolutionary War concluded.
Unless the poll were in the context of off-battlefield accomplishments, Washington wasn’t Britain’s “greatest foe” by any objective measure. That would be Hitler.