I've been thinking about that garden. It's very large, and would be a lot of work to maintain, looking as nice as it does.
IS has been in ill health, which makes me think he was probably not looking after the garden in recent times, before Helen went missing. I'd say they had a gardener. Especially since IS went away on holiday and the photos of the garden on Monday show it looking immaculately tended, not overgrown.
Makes me wonder if the gardener was given any specific instructions, or raised concerns with the police. They did seem to hone in on the garden, as if they had had a tip off. Maybe.
The other thing I was thinking about was whether Helen has been there all this time. The police worked the garden before, possibly not that thoroughly but it would have been easier presumably to spot any recent digging or new patio at that stage.