In terms of valuation and interest rates, should we use the US rate or the rate of the country of which you are valuing a company in?

Let's say you are valuing a company based in England. What interest rate should we use to determine our own discount rate to apply when valuing the company? Would we use the interest rate of England (or whatever country the company is based in)? Would we use the interest rate of the US? The interest rate of the country that we live in since it affects our buying power?