Boiling point of water on Great End

I was boiling the kettle for tea on Great End. I am aware that you need water at 100 degrees Celsius for decent tea. I'm also aware that water boils at a lower temperature with altitude, but I had never thought it might be noticeable in Cumbria. Great End is 910 metres. This website suggests that the boiling point is already down to 97 degrees Celsius http://www.engineeringtoolbox.com/boiling-points-water-altitude-d_1344.html I'd never thought about it but parts of America are high enough for this to be a problem domestically. Since it seems measurable, there's a project for the autumn with a thermometer on the Cumbrian mountains.