IIRC a Tornado managed to guide a King Air across Scotland after latter lost instruments in poor weather. On another occasion a Tucano was sent up to help a Cessna pilot who went blind in the air to safely land at Leeming.
When a F3 and Typhoon flew formation with a Spitfire at last year's Leuchars airshow, they were both flying fairly steep angles of attack to keep up (down?) with the Spitfire.