Not LGB, but the advert (Blakeys) is a Leeds advert on a Leeds steam tram trailer. Blakeys were famous for their cast steel boot protectors and their foundry was at Armley next to the railway station (on the Bramley, Pudsey line).
Like many towns and cities, Leeds had many local advertisers which, even if their advertisements were not kept local, their manufacturing base was in the city. One of the latter was J.E.Mather, manufacturers of Black Beer.
Since 1970, I have been involved in trolleybus preservation (no longer on a hands-on approach unfortunately) and I once met the late Bert Mather - a Leeds Alderman and one-time member of the Transport Committee. The occasion was to seek his family firm's permission to re-instate the 1950's Mather's Black Beer advertisement on the side of a restored trolleybus. This was gladly given and duly professionally re-instated - complete with Black Beer bottles suitably painted in "perspective" so they didn't seem to be falling off the bus!
However, Alderman Mather told the story of meeting the Rolling Stock Engineer one day and asking how one of the trams was doing "was it out all day?)" yes was the reply. Funny said the Alderman, because I've seen it stuck in the works minus trucks!
This was one of the ex-London HR2 cars which sported a Mathers advert. No doubt he asked for compensation (extra days to be added to the contract).
Mick