Investing in Great Britain/Northern Ireland

I spoke to a guy in IR & he said that: "In most situations non residents are not liable for capital gains". He said that if you were in the business of acquiring property doing it up & selling it on every few months it may fall under consideration of being a trade.
The main point is though that if you are non-resident, not ordinarily & non-domiciled then then you are not liable for CGT, he led me to this document: http://www.hmrc.gov.uk/worksheets/sa109-notes.pdf
See Table 5.