This is a nonsense comment. Easy to get to by train from London. Don’t be discouraged by this comment.
A lot of foreigners seem to conflate London with the entire country in a way that doesn't seem to happen for other countries (you don't 'go to Paris' and actually stay in Marseilles) and some people outside London especially understandably don't like it.
Not that it's an unreachable distance away for a trip based in London.
Since you brought up Paris, I'd compare it to Versailles.