An Iranian colleague tells me that in his view the place to go for authentic, home-cooking style Iranian food is Ealing Kebab, website http://www.ealingkebab.com. It is a modest sort of place, not expensive at all, with authentic Iranian dishes such as Zereshk Polo - rice and barberries served with chicken (and he said you can't get barberries in the UK!) - cost £7.00. For the more adventurous, there is also soup with sheep's tongues and feet. On the whole the menu isn't massive, which isn't a bad sign at all in my view.
Unfortunately I don't travel much around London, apart from my daily commute from South London to Essex (via Thattukada!) so I can't see myslelf getting there in the forseeable future, if ever, but perhaps some Ealing based Chowhounders could report. I'd certainly like to try it.
My Iraninian colleague reckons that Mohsen isn't as good as it was, which is a tragedy for me as I still haven't been able to go there yet, and now it seems I've missed its glory years. On my suggestion he is going to try Simurgh in Covent Garden, the only Iranian restaurant in London I've been to, and report back.
PS - anyone tried La Movida, the Spanish restaurant in Battersea yet?