Hi Railer, Generally the 42'9" wagons are referred to as LPs,and the 47' as LXs, The LPs and LYs were the first into service in the early seventies, There are no LYs in service now as their bogies became non standard, The LYs were used predominantly for Guinness traffic,along with the LPs and LXs. The LXs came into service during the late 1990s as it was found IE would need a longer wagon to cater for the 45' 9'6" high containers-they were extended by using the buffers and headstocks from former fertiliser wagons and indeed some of the bodies of the fertiliser wagons were used also From what I'm told there are now a sufficient number of LP wagons refurbished for the forthcoming biomass traffic. An LY wagon with the now non standard bogies.