Beagle, your remarks and those of the TV programme that gets repeated every now and again are a vile calumny on the good name of Boscombe Down. The true story is as follows:-
There was indeed a Fuse 13 on the Gnat. This protected a circuit which restricted the aileron travel to 12 degrees when the U/C was retracted while allowing the full travel of 15 degrees when it was down. This protected the wing and aileron from overstress at high speed while permitting full aileron for manoeuvrability in the circuit. With Fuse 13 fitted and serviceable the aircraft was cleared to rapid roll (full lateral stick, fast as you like) up to about 500 knots and 5g. The Red Arrows realised that they could roll faster with Fuse 13 removed, but far from acting irresponsibly they asked Boscombe if they could rapid roll with it removed if they kept to a more restricted flight envelope. This was investigated with the Design Authority and it was determined that they would be OK if they stuck to 1g rolls at no more than 350 knots. They were happy with this and a proper clearance was issued. The Arrows used it to do absolutely mind-boggling 9-ship formation twinkle rolls the like of which I have never seen since. All those small aeroplanes rotating about their individual x-axes at circa 360 degrees per second while only feet apart had to be seen to be believed. (They always overshot by about 10 deg at the end and had to correct back to wings level. It didn't spoil the effect because they all overshot by the same amount, but they tried very hard to correct it. Eventually someone discovered that the roll acceleration of the Gnat was so high that the eyeballs were rotating axially in the sockets and giving the pilots a false impression of where the horizon was.)
Everyone was happy, not to mention legal, till an ex Red Arrow who had returned to instructional duties flying a Gnat with Fuse 13 in place developed an unusual demonstration for his students. He decided to show them how fast a Gnat could roll by applying full (12deg, fuse in) lateral stick and helping the aircraft round with rudder. He thought this was OK because he did it within the restricted Red Arrows rolling limits. The fin, however, had other views about full rudder at 350 knots and broke in protest. The RAF system then missed the point, over-reacted and insisted that everybody fly with Fuse 13 in place. End of super formation twinkle rolls.
Incidentally, the early development Hawks had a similar restrictor on the aileron angle, in this case being operated by a mechanical plunger on the undercarriage. During development it was discovered that with judicious optimisation of the gearing it was possible to achieve adequate roll rate at high speed, adequate manoeuvrability in the circuit and good handling without the restrictor and it was deleted. MoD asked for some money back in respect of the restrictors which would not have to be manufactured, but I doubt they ever got it.