From King’s Cross St Pancras, take the Piccadilly line directly; if crowded

https://emilianoqxrs791.cavandoragh.org/national-rail-to-heathrow-routes-transfers-and-tickets-explained

From King’s Cross St Pancras, take the Piccadilly line directly; if crowded, consider one stop on the Circle/Hammersmith line to an easier interchange at Paddington.