Yes, but they only drive on motorways at weekends because they wouldn't survive for long if they tried driving like that during the week.
Bear in mind that in UK it's illegal to overtake on the nearside of motorways, no-one can get past once they begin the "I'm doing just under the speed limit and I'm not moving over for anyone" stupidity.
Other than flashing them your brights there isn't much that can done with these lunk heads...