I remember Reader Bros well.They used to pull Dutch trailers off the dock and drop them in Humber Street (I think) loaded with lettuce and I used to go and load my wagon when I worked out of Sheffield market in the late 60s.In fact there’d be one or two loading off the same trailer and you just helped yourself,usually at night.When t’wind was blowing those boxes of lettuce were a bind to keep on your trailer when loading 'em.
Haltemprice Transport was another company that did the same thing.
Link Transport used to deliver wet fish to the chippies at night,just dump it in the doorway and away to the next shop.I used to see them regular when I was on nights delivering for Littlewoods,usually round West Midlands.
Do you remember Henery Brothers who carried fish? They had “Fish is your life” on the side of their wagons 
.They had a nice fleet,Arrow Bulk Tankers and I think they were called Easthaugh Brothers before that.