Richard A Thackeray
Legendary Member
I did look later, in the evening, after thatIt's not the bridge number because it's Altofts Bridge, Number 3, more info here, more likely to be a distance marker, I'm guessing to the Ouse at Goole
Yes it is a milestone, as evidenced by this 25" OS map, from 1908
Marked in the standard way as 'M.S' (north of the over-bridge)
http://maps.nls.uk/geo/explore/#zoom=17&lat=53.7051&lon=-1.4619&layers=168&b=1
In that case, it will be to Goole, as that was the destination of the A&C N
I grew up not that far from the Canal. & can remember seeing the 'Tom Puddings' on the Canal, but in limited numbers, & Hargreaves barges moving sand/gravel along it