I work there, they've put an extension to the existing warehouse yard and although you can't see much you can see small fragments of brickwork in the holes for the supports.
http://maps.google.co.uk/maps?ie=UTF8&ll=53.424007,-3.050715&spn=0.001072,0.003433&t=h&z=19 The rectangle below the small red thing (it's a container) also looks like it's an original part of the bus/tram depot. I have no idea what the big grey rectangle behind the building is though, never seen it before.
Although proposals to build a tramway had been put forward as early as 1870, it was not until 1878 that the Wallasey Tramways Company (authorised by the Wallasey Tramways Act of the same year) began to construct a single-line horse tramway between the ferry landing stage at Seacombe, via Brighton Street to Egremont, along Liscard Road to Liscard, then north via Rake Lane to Upper Brighton, terminating at the depot in Field Street, just to the south of New Brighton. The line opened on the 28th June 1879, with the service being maintained by the initial fleet of Starbuck single-deck cars (Nos. 1-7), joined in 1880 by five Eades double-deckers (Nos. 8-12).
Give that man (?) a coconut. They put them there because the horses would not have been able to pull them up Rowson street so they either started from Rowson street or Seabank road and not down in New Brighton proper. During the second world war the old tram sheds were used as a temporary mortuary.
Oh yeh, a guy I know nearly killed himself cutting through an "old" electric cable in one of them. It was live.