Did you have the serious gales at the beginning of last week? Or are you in the area of the UK that has had major drought problems? Trees will shed their leaves in order to loose less water if they are really stressed. If you are in the drought area leave the hose under the tree on trickle for several hours and repeat regularly.

we are in an area that has been hit by drought , and I did wonder if it was just that, but I understand that lots of people have lost smaller bay trees, and wondered if I will lose this big tree. Since we have had some rain, the leaf drop seems to have been less. Hopefully it will recover. Thanks for your help

Even though you have had some rain I'd still get the hose on the tree. Unless you have a monsoon for the next month the ground is going to be bone dry and normal rain isn't going to have enough effect.

Agree with MG - leave the hose trickling at the base of the tree for a couple of hours, rain or no rain. I'm not sure what you mean by 'sweet laurel' and am assuming its Bay - lots of them did get damaged by the winter, you're right, but most were in pots - remove any obviously dead wood if no regrowth occurs in the next fortnight.