Visiting the UK for tourism on a Business Visitor visa, after previously visiting the country for business

I already got Business Visitor Visa (Multi Entry) for UK in previous year, when I participated in the conference in London. My Visa is not expired yet. I want to spend my holiday in UK. My question is, can I enter to the UK for tourism purpose with my current Business Visitor Visa? If yes, can you please, show me related government rule or like this ? I don't want get rejected in UK airport!