Is British ale/beer bitterer than elsewhere? I've heard it is, but can't confirm as I've never tried it. This might be a piece of evidence in your favour if so.
It's worth remembering though that from the '80s[0] onward Lagers would've dominated beer sales in the UK. So while we could buy more bitter beer than available elsewhere, we often didn't.
[0] - I've no source from this, it may have started earlier but at a certain point in the mid-late 20th century we shifted to lager. Often very poor quality ones like Carling, Foster's or Tennents that would not compare favourably to those available in Germany, Belgium or Czech Republic.