Judging by the pics the plant looks quite healthy, apart from some of the leaves being nibbled, possibly vine weevil? don’t forget all evergreen gradually shed their leaves, are these fallen leaves that are just decaying or were they on the plant, are you keeping it watered through long hot spells? Could be some type of leaf spot.

Thanks Julien. The leaves are on the plant but I have removed and discarded them. I will keep an eye on it and as you say give it some more water.

Yes, they are just old leaves that the plant has shed. The nibbling is probably Viburnum Beetle. Just clear any old debris from beneath and spray with systemic insecticide to break the beetles' cycle.