Is the risk free rate of return on a given market equal to the central bank of that country?

I am currently doing a project on mergers and acquistions, i have to reference a risk free rate for the FTSE 100, would it be correct to assume that the rate of return of investing in the central bank of england aka the bank rate is the markets fisk free rate (rf) Any advice or [...] http://bit.ly/mti1Cv