Does anyone know what this GWR▸ building was used for. It has the railway name painted on the side of the building.
I have seen the building a few times in the regenerated area of the docks - it may well be that there are interpretation board there. In the meantime, according to the label on a picture in the Steam library
https://www.steampicturelibrary.com/places/docks/great-western-railway-goods-depot-liverpool-19754333.htmlGreat Western Railway Goods Depot, Liverpool
The GWR Goods Depot was situated at the Manchester Dock Depot on Mann Island and was part of the Liverpool Dock complex. Cargo was brought over from the GWR's premises at Morpeth Dock in Birkenhead and then distributed around Liverpool by road vehicle.
and that looks perfectly plausible - probably correct, though a simplification. The Ian Allan pre-grouping atlas shows many, many rail connected good depots in our cities - some very complex maps - but this GWR depot is not shown, which hints to me that it had no rail link. Liverpool was one of those major cities where all the rail companies competed for goods - perhaps the more so with it being a port - but it was very much on the edge of GWR territory (just off) and the depot would be a logical point of presence for them.
Other pictures / references at
https://www.geograph.org.uk/photo/3514253 and
https://www.railforums.co.uk/threads/gwr-in-liverpool.25298/ 
