When you say easyJet offer the service do you mean they officially offer it or that every time you've travelled with them you have received your buggy at the gate?
Tudor, looks like you're right - I've just been lucky. The extract below is from the easyJet website FAQ - you can take the buggy to the door, but no promise about when and where you get it back:
"
Pushchairs, buggies, and travel cots can be taken right up to the aircraft steps and/or door, where they will be taken by cabin crew and stored in the hold. You can however check it in with your baggage at check-in, if you wish to do so. Full size, non-collapsible prams cannot be accepted for travel.Pushchairs, prams and travel cots do not form part of the baggage allowance and therefore no fee will be charged."