"Dun" is very common in Irish Gaelic, as are "bally" and "rath" (town and ford). Here in Brittany names often begin with "Ker" (town), "Plou" (parish) or "Lann" (holy place). My non-French speaking family has great fun with place names here such as Pleucadeuc and Plouhinec (pluck-a-duck and Bloomin' Heck). I won't tell you how they pronounce Languidic...!

The words "dun" and "hill" together also make up a famous brand of tobacco products. Probably not a coincidence.
In my (so far fruitless) search for an answer to Céline's fiendishly difficult question, I visited a site that says "dun" is also to be found in Dunkirk. Interesting - I thought it had to do with the sand dunes which I believe are plentiful in that attractive seaside town.

I put my money on London.

Answer on Monday! I'm out interpreting today and failed to prepare the answer last night.

I doubt Dunkerque's name comes from Gaelic. The town is located in the Flanders and Flemmish (Dutch) used to be spoken there. I think it is more probable that name comes from Dutch: Duin (dune) and Kerk (church). The town's name is actually "Duinkerke" in Dutch.
Cheers,
/ml

(Comes a little late to the party.) Ah,Inglenook! It was (is?) the name of the house, in Preston, Lancashire, that I grew up in. Warm memories.