Hi Phil. Probably lack of nutrients, but a photo would be useful. Plus, is it in the ground or in a pot? How large and old is it?

Photo essential, unless you know which variety of 'laurel' it is (cherry laurel, spotted laurel, bay laurel...)

Many different causes of yellow leaves, Phil. Photos would help tell which are in play. I suggest an overall view of the bush, a close up of the leaves in the process of turning yellow, and a close up of the stems the yellow leaves are attached to.