Here's the info - not the best graph in the world but is showing the trends:
http://www.houseweb.co.uk/house/market/graph.html
And the raw data here:
http://www.houseweb.co.uk/house/market/irfig.html
I guess it is not so much that the rate is higher than current amounts (as we can see the figures were as high as 15% at one point - but even if they never went much higher than 6% there is still the peace of mind that you know how much you will be paying every month until the end of the term. Good info BTW Towny.