1) use spreadbets; or
2) use CFDs; or
3) purchase ADRs or similar on a foreign exchange; or
4) find a good lawyer and tax advisor to set up something complicated and expensive off shore (I presume this can be done)
Remember too that although a stock may be UK-listed, it may be classified as an Irish stock - the downside is that you pay 1% stamp duty on Irish stocks instead of the usual ½% for UK-listed UK stocks.