And as for it costing 25 quid, the cost of operating the lounge - the rent, fitout, staff, cleaning, food, beverages, utilities, etc - doesn't just come from a magic money fountain. Airline lounges are operated as separate revenue and profit centres (whether it's run by an airline or a third party) with management who are responsible for how profitable it is. If you want a 2nd traveling companion to get in with you, your options are:

1. Buy them a business class ticket, where the ticketing carrier will pay the lounge operator the 25 quid fee out of the ticket price you paid.

2. Fly them around often enough that they reach an elite level where they too get lounge access, where either the ticketing carrier or the airline they are elite with (I think the former) will pay the lounge operator the 25 quid fee out of the ticket price you paid. Even if the airline itself operates the lounge and not a partner airline or 3rd party, the lounge will be a separate P&L within the airline, and the cost of the lounge access will be a revenue for the lounge and a cost for the flight division.

3. Have a Amex Platinum/Diners Club/Priority Pass/some other card based access system, where the card issuer will pay the lounge operator the 25 quid fee for accessing the lounge.

4. Pay the 25 quid lounge access fee directly to the lounge operator if that's allowed.

5. Smile, walk up to the lounge agent, hope they don't know the rules /don't care about breaking rules/got out of bed on the right side this morning and like the way you look/realise just how special and unique your situation is and let you in.

If none of the above work, accept it, head off to spend the 25 quid somewhere else in the terminal, or see if you can send your wife and child in while you wander the terminal, but don't waste time getting upset someone didn't break the rules for you!

If they started breaking the rules for every status based economy passenger with a 2nd (or 3rd, or 4th etc) traveling companion who is a child/dear friend/important business colleague/parent/grandparent, there would be no point for the rule in the first place, and there would be even more threads on FT about how dare airlines let lounges get so dirty/overcrowded/impossible to find a seat in/noisy/the food runs out so quickly...