I think he means primarily there's a lot of existing airlines at LHR who would use more slots if they existed. We've had this conversation before but if I recall 50% of any new slots are initially allocated to existing operators and 50% to new operators defined as operators with 4 or fewer pairs of slots per day. There are many interesting questions about how the process of allocating a massive increase in slots would actually be managed given issues of 'use it or lose it' and organising the terminal capacity, slots and gates depending on who gets the slots.