Wasn't one of the keys to a good Dayglo paint job the matt white base prior to the dayglo application?
Guess that rather depends on whether the JP was painted in the silver/dayglow scheme or if it's from the later (and longer) period when they were painted silver (and subsequently Light Aircraft Grey) with fablon dayglow patches (aka "Fabglow"). I've always thought that the later stick-on dayglow schemes looked more attractive.
It kinda saddens me that the RAF churn-out a couple of specially-painted Hawks (and Tucanos) every year and they're always the same variation on a tired old (black) theme apart from the "Spitfire" scheme last year of course. Wouldn't it be brilliant to see a Hawk in Light Aircraft Grey with dayglow patches - just to see what it would have looked like?!