Hi, welcome to OSM.  Thanks for identifying this maxheight location and limit.  Can you put the maxheight = 4.8 on this one section of Foul Lane that goes under the bridge rather than on the rail tracks (where the height is not limited here).
If you ever need it there are notes on tags like this https://wiki.openstreetmap.org/wiki/Key:maxheight
(and any other tag you want to look up) should you need to check anything.  Happy mapping, Cebderby (Clive)