my dad and i worked on nackinton farm in canterbury.the farm had there own pack house with there own vacuum cooler and ice making machine.as for the lettuce rig the rig whent over 5 beds of lettuce at a time a lady would cut the lettuce behind the rig and put the lettuce onto table on the back of the rig where a woman standing on the rig would take the lettuce and put it on a wrapping table where the lettuce would be put in clingfilm and sealed with a hot iron which was powerd by a generator which was fixed to the front of the tractor(flat 60-80),the lettuce was then put into a box and transported to the packhouse on ex-army unimogs and bedford lorries where thay where vacuum cooled and put into cold storage to go out on artic lorries to supermarkets