A small number of Scotland Yard detectives (from Special Branch) were posted to Le Havre to detect suspected enemy agents and spies (and in the early days of the war journalists!) but it's unlikely they had any sense of humour! Special Branch was more aligned to the embryonic MI5 than Scotland Yard at this time and enforced the Official Secrets Act enacted in 1911.
Le Havre was the main port of embarkation and disembarkation and the gateway to the sprawling conurbation of depot camps such as Etaples and Rouen (Richard Holmes has an excellent description in 'Tommy'). There was a lot of work for the MPs of all nationalities, there are documented cases of deserters being arrested and held there.
Before the war Le Havre had a major shipbuilding yard which along with the port and city was obliterated by bombing by both sides but especially the Allies in WW2.
I don't know but think it likely that the offices and facilities of the yard were requisitioned during WW1. According to a modern guide book the yard was close to the old fisherman's district and very near the harbour.
As a retired Scotland Yard detective I would really like there to be a link, but I think it more likely to be the shipyard. Although the really fascinating question which you actually asked and I don't have an answer to is what went on there. You've set some hares running for me - thanks, I think
Ken