Saw an electrician's van up near Lochcarron once with, "The Vital Spark" on side - cosy chuckle. However a mixer lorry down here, near Hastings had, "William the Concreter" on it. Louder groan to start with but doesn't really have the sustaining power. I won't mention gardening contractor called "Law'n order". Any more street puns ?
In Edinburgh there are two plumbing/heating firms - "Specific Heat" and "Scottish Thermal Unit". But I wonder if these might be a bit esoteric for the wider audience without higher physics pre 1980 (or equivalent).
Higher physic eh. I've heard these southerners mention uppers and downers but I suppose higher physic must be some sort of medecine - a tonic like Irn Bru or Buckie, maybe ?