I guess companies were you already worked 30 hours (6 hours per day of effective work as in many "mental work" jobs). I'm not from UK, are any manufacturing companies on the list?
They're either unrecognisable (so quite small), or where they are recognisable they seem to be charities or CIC (community interest companies). That latter group of companies are structured so that profit is not the raison d'être of the organisation, so work/life balance is likely to be considered a higher priority than squeezing every last bit of utility out of an exhausted workforce.
if you don't feel exhausted from time to time it means you potential is wasted. Community interest is important so it's important that employees at such companies utilize their full potential. If decision was made because of signs of burnout it means they needed more employees.