[CdM] NO, did not die in a duel.
[Tuj] NO, nothing notable named after him (well, numerous stories based on his life and death, but nothing like I interpret your question to mean).
[FGZstar] NO, did not die in the Great Fire.
[INJ] NO, I should say not mainly known for his death.
I think you guys are a bit too focused on the death angle. It's somewhat important, but not necessary to figure out how he died to find out who he is. And it's not as unusual as you're making out given the circumstances. You might do better to try to determine what he's actually famous for.

[Raak] I think the best answer I can give is PROBABLY he was involved in a war in some capacity. I shall add that the capacity in question is not directly what he's famous for but closely connected with it.

[Raak] I didn't know he was British ;)

[Raak] What Tuj said, so NO :)
[Tuj] NO, unless you define the field very broadly indeed.
[Raak2] NO, he didn't invent anything that I know of.
I'll clarify: what he is believed to have done in wartime is essentially the same thing as what he is famous for doing, but under different circumstances. You might like to explore the angles from the last couple of YES answers.

[FGZstar] YES, but he didn't become famous until the 18th.

I will clarify that: he was notable while he was alive, i.e. it isn't a case of some ancient person being (re)discovered in the 18th century or anything like that.

[Raak] NO, not involved in building.
[INJ] NO, not known for his beliefs.
[CdM] NO, no medical connection.

OK, we're looking for a British man, born in the 17th century, became famous and died in the 18th. He died violently, but not unlawfully (subsequent research suggests there might have been some doubt about the legality of the circumstances leading to his death, but that's probably misleading; he certainly wasn't murdered) although he was not executed, nor killed in a war or a duel, nor did he commit suicide or die in an accident. He is not mainly known for his death (although the manner of his dying is at least somewhat celebrated).
He spent a lot of time in boats, but was not a noted navigator or explorer. Nor was he a politician, scientist, writer, aristocrat or inventor, and he was not involved in the arts, construction, geography or medicine.
He is believed to have been involved in a war in some capacity closely connected with the way he became famous. He has nothing notable named after him.

[Raak] YES, I should say justifiable homicide.
[Tuj] YES, he was an infamous lawbreaker.