As one who remembers the time when, if you owned an eligible car, you could send in an entry, have it accepted, turn up and go racing I begin to feel very old indeed!
Under modern cartel rules not only would Rob Walker not have been able to enter his cars for (e.g.) Stirling Moss to drive, it is highly unlikely that the man from Cheshunt would have been allowed to enter his Lotus cars at Monaco in 1958, engined as they were with 2 litre Climax motors in a 2½ litre Grand Prix and driven by a couple of sports car drivers (Cliff Allison and Graham Hill)