Get business visitor visa if already hold family visit visa?

[rosb]

I am South African. I am applying for a 6-month family visit visa for the UK, to go and visit my sister (a UK citizen) later this year. Either shortly before I enter the UK, or while I am in the UK, there is a chance that I may be asked to do some work for a non-UK company handling a short-term project in the UK.

1. If I am outside of the UK when I get asked to take the job, but not in South Africa, would I be able to apply for a business visitor's visa? Note that I would have an existing valid family visit visa in my passport.

2. If I am already in the UK, having entered on a family visit visa, would I be able to apply for that to be converted to a business visitor's visa?

3. If I am already in the UK on the family visit visa, would I be able to work legally for this non-UK company for a period of about three weeks on their project in the UK? I would be paid out of Singapore into my South African bank account.

Thanks,
Ros.

[Lucapooka]

1. Yes
2. No.
3. No.

http://www.ukba.homeoffice.gov.uk/visas ... ctivities/