In theory yes, but in practise, you cannot completely 100% specialize without taking on an asymmetric risk (that of the outside party not selling you food due to their own or some other crisis).
The risk is asymmetric because your specialty (tea) isn't an absolute necessity (may be 'cept to the brits), and yet, you _need_ food (an absolute necessity).
The risk is asymmetric because your specialty (tea) isn't an absolute necessity (may be 'cept to the brits), and yet, you _need_ food (an absolute necessity).