The smoke is indeed diesel with dye.
We once had a suggestion from an early African customer who wanted to do a 'Presidential Flypast' - using Trichoethylene ( Genklene, now banned ) as it produces white smoke when burned.
Can't remember if they were going to fit pods or maybe put in the fuel ? Anyway it resulted in Flight Test's quickest ever response; the white smoke happens to be phosgene gas, the result might have been like the scene in 'Goldfinger' where all the troops keel over as the aircraft pass !
We had another request from a customer who wanted green smoke; it's actually quite difficult to get a good solid colour from a Hawk's Adour, as it runs relatively cool.
After days of testing a Hawk with various dyes static in the middle of Dunsfold, Flt test's Reg Hippolite & team got a good solid green.
It was a calm day, and the smoke drifted slowly across the 'field.
Shortly afterwards the Airfield Manager received the snottiest phone call in history, from a local woman who'd just had her hanging washing dyed bright green !
I think some slight compensation was made, I just wish I'd been able to go and photograph our results...