The boat trains were very seasonal, both between summer/winter, and individually by day of the week. There was quite a lot of ecs running to keep stock available at both ends. Each mainstream ship departure had a set with a BEP buffet in it, but as the ships held up to around 2,000 passengers each there were commonly buffet-less reliefs, running just before Down to Dover and just behind on the Up journey. Sometimes even the most popular ships were duplicated with relief vessels, and then there was a considerable extra effort to run supplementary services.
At the Victoria end the international passengers tended to turn up well before time, in substantial numbers, and were a considerable nuisance on the concourse, so it was good to pack many of them into an earlier relief and send a trainload down to Dover, where they in turn had big queues to handle before the ship opened.
The MLV were added to the London end of these trains, which suited both Dover, where they were shunted on batteries forward from the train at the platform, and then in parallel down the quayside, where the baggage was loaded into rope slings and craned aboard. Likewise at Victoria there was a customs inspection point at the barrier of platform 8, and possibly others, where arriving checked bags were taken inside to be claimed. I have never quite got how this worked between having customs inspection done at either Dover or at Victoria, nor how the bags might be in the main train but their passengers in a relief, arriving in another platform. On Down journeys the driver was in the 1/3 width CEP cab, but on Up journeys they had the full width cab of the MLV. I believe some busy services had two MLVs, a 14-coach train, making them the longest emus on BR.
At a very youthful age, probably in 1962, we travelled by one such on the return from Ostend, and patronised the BEP buffet, where I was, as some sort of supposed huge treat, given my first ever Pepsi-Cola. It was not chilled, served tepid, and I disliked it not only then but ever since, preferring its well-known rival. Also still recall that buffet car had a small plaque inside saying it was the first installation of air-conditioning in such a vehicle. Many years later I found out which BEP set it was that had this pioneering novelty.
