Could the UK be self sufficient in tea?

We now grow tea in Scotland [1]. We have heard about climate change hitting coffee production [2] - well speaking as a tea drinker I don't much care about that but if I had to reduce my tea intake I would be seriously upset. It doesn't bear thinking about. So here is a back-of-the-envelope calculation for how much land it would take to grow all our own tea.

• Our tea consumption is 157,000 tonnes [3]
• The yield in India is about 1600 kg/hectare [4]
• The sun's energy in the UK is only 50% that in India [5] so let's assume we have half the yield: 800 kg/hectare
• We need 196,000 hectares - about 10% of the area of Wales (0.8% of the area of the UK).

Well, that is a lot of land, but surely for tea it would be worth it. :-)

[1] Home grown tea served in the Balmoral Hotel (BBC) March 13th 2015.

[2] How climate change will brew a bad-tasting, expensive cup of coffee (Guardian) March 2014
[3] Tea import-export trends in focus at Dubai forum (Middle East Association) April 2014
[4] Tea yields compared (Tea uncomplicated: the simple leaf blog). October 2006
[5] Using PVGIS