Jump starting points towards low or knackered engine battery.
If it won't start with jump leads then either the jump leads are thin rubbish ( you only need one to jump off the cabin batteries positive to the engine battery positive so use both leads together if they are thin ) OR you have a bad connection, you did say that the negative got hot? Classic bad connection.
Run it till the batteries are charged which is not 2 hours every day or so, you will destroy batteries doing this.
If on the Oxford, ask Tony to come and show you how to charge batteries and find your problem.