Re: Seems to me that adoption of eLoRaN would be a better post brexit solution for the UK...
The trick is not to send embryos frozen but in ambient temperature media. A bit of a problem since fertilised eggs/embryos will arrest and not develop whilst in it so it is less ideal. But transporting 37C media in a CO2 incubator is rather difficult. But not entirely impossible. Trucks exist with power sockets.
When the lab I first moved to here in Dundee moved up from London the -20C and -80C freezers were simply loaded onto the trucks, plugged in and driven up.
I did this once, getting mice from Paris to Dundee as morulae (balls of cells stage of development: 1 becomes 2, becomes 4 etc) in a 5ml screw top vial by fast courier. They were then implanted into recipient female mices and miraculously baby mice came out the other end after 19 or so days.
It had to be done this way because of rabies regulations here in the UK. Stupidly lab mice are covered by this and applying for the permits was and probably still is a nightmare. Getting the mices as embryos also meant they could go straight in behind the barrier into the clean rooms.
I know a scientist in Geneva who wanted to send mice to some people in Paris. Flying from Switzerland was a problem with regulations. So, he drove to the French part of Geneva airport, put the mice in his pockets and took a domestic flight to Paris.
I have also got mice from England by dint of driving from Dundee to a hotel in South Queensferry and transferring boxes of mouse cages from the boot of one car to ours. A very suspicious looking activity carried out in broad daylight.