Of course in the UK most of us would have turned off our transponder to avoid the GASCo police. 
In these low speed intercepts, the Mirage/Rafale can hold about 110 knots a very high AoA and lots of thrust. It therefore shortens its endurance.
The worse case is when a Mirage is sent to recover a slow GA plane lost over a layer or in and out of IMC. Then it must stay close to the target for a long time without flipping it upside down with the jetblast. It happens sometimes. In Info Pilote there was a story about a 152 lost in the mist. It was led by a Mirage to a long final at Tours IIRC. Both pilots were totally fried once landed.
Airborne_Again wrote:
There must be something more to it.
Maybe they suspected the Brit’s of trying to smuggle some ham sandwiches into the EU
172driver wrote:
Oh, I know them, but at least in the US the initial contact is by flying alongside.
Yes, but also rocking the wings and turning navigation lights on and off irregularly – and:
If the intercepted aircraft is not able to keep pace with the intercepting aircraft, the latter is expected to fly a series of race-track patterns and to rock the aircraft each time it passes the intercepted aircraft.
Which will be the case for most GA being intercepted.
An aircraft simply flying alongside means nothing, other than flying alongside, saying hello 
How many would instinctively fly away from a fast jet coming up alongside?
Good point. It’s a bit like a kick in the balls. The “right” defence is to tilt your pelvis forward. In theory.
