Strange one this, according to LTN airport’s website the inbound flights are operated by a 767 until June 16th when an MD80 takes over but all outbound flights are operated by MD80’s. The latest rumour is in fact that a 767 will operated out of Luton and that the start date has been shifted from May 15th to May 19th.
What is a little worrying is that if you do an Internet search for cheap flights to Lahore you won’t find this service.