Where in the UK can you buy Lipton iced tea or Nestea?

I did find some Lipton iced tea, I believe it was, at Lord's convenience store on Brompton/Cromwell Road in ?Kensington? in central? London...near the London Oratory/Harrods/Victoria and Albert Museums. The only problem was that it was flavored lemon or something...whereas I'm still searching for just plain sweetened iced tea.