Put simply we don't! It would be cruel and also a wee bit illegal. Royal Mail are allowed to ship very limited types of live animals, and Lobsters are not one of them. 

Instead we use an approved livestock carrier APC who distribute live fish and other animals for the UK pet trade. Our view is that just because our Lobsters are going to be eaten that doesn't mean that we should be cruel to them beforehand. So we look after them at every step of the journey from Sea to you. We pack them with enough ice gel packs and seawater soaked humidity pads in sealed polystyrene boxes to last for 60 hours, then we send them on an overnight service.

So far as we are aware our carriers are the only national parcel carrier in the UK who are allowed to ship live fish and crustaceans.