Viburnum tinus under attack from the dreaded Viburnum beetle.
Soak with a systemic insecticide, prune off all the affected leaves and burn, not compost. Hope!

Thank you, Owdboggy! The smell was driving me mad until I tracked it down to the bush - I thought it was the drains :-0

You're not having a lot of luck are you Chilecat. Seems to be a lot of this about recently.

Don't forget to clear up any fallen leaf litter and I would scoop up and replace a layer of soil beneath the shrub where the grubs settle as they pupate into the beetle.