Don't always trust Monty. They can survive in sheltered spots. In Spain and Italy they get minus temps and snow.
You see them regularly in that London especially in and around office block courts with microclimates that are suitable.
If in the midlands you could plant one in a pot- take it inside in the winter, or even build a temporary mini greenhouse round it in the winter.
If you did this you could cover the frame in fleece or polythene. If you use polythene then leave the south side open, or attach a batten to the bottom of that side so you can roll the elevation up to allow for ventilation.
Bubble wrap or hessian around the pot and stem of tree.will be beneficial .
I left 2 small ones out at work in terracotta pots with no protection at all this winter in Cambridge, they are fine.
https://www.google.co.uk/search?q=w...K9LTbAhXkLMAKHShEBCYQ_AUIEigC&biw=768&bih=937