Well it was eventful!

First time towing two.  All went well - drove to area, unloaded, rode, loaded, drove back.  On way back a lot of stamping.  When we pulled up to see why the stamping - the central partition had come slightly undone at the base putting it at an angle.  Luckily neither were hurt and both stood quietly out of trailer whilst I fixed it with a wheel wrench and some athletic ability.  We're going out again tomorrow.  Cilla is working on her breathing as we speak!