http://www.bbc.co.uk/news/uk-politics-38577336

I've never understood this - it's not like you suddenly forget the companies you've invested a lot of money in.

depends on how much money you have

A blind trust doesn't just hold the shares, it's allowed to trade them. So over time, even if the investments were known when they went in, there's nothing to guarantee the money is still where it was. That's the 'blind' part. It's a little bit of an issue that by definition the investments the trust makes can't be made public but in general I think it's the best option that's practical.

I have many, many reason to criticise Theresa May but this is not really one of them. This is what all PM's for years have done.