Wills, if you want low caffeine tea, don't go for stuff that's been tinkered with (pardon me Tinker ), cultivate a taste for redbush, which is naturally low in both tannin and caffeine. Might even be caffeine free...
We'vre tried several brands and the nearest to "real" tea in terms of taste is the 11 O'Clock organic brand with the little girl being served tea in the nursery. It really is delicious and we drink it most of the time now.