Ok steve(DP puts GOD head on

)
Swirls? little round milky scratches?
i would try Farecla G6 or G7(most spray shop suppliers will stock a tube of this stuff-they'll try to flog you G3 which is designed for modern 2pack applications)-its more user friendly but good old t cut is as good as any providing you have the patience.
if compound doesnt work you could try wet flatting it VERY CAREFULLY with some handsoap & 1500 grade wet & dry paper.use STRAIGHT LINES not circular motion. then once its got a dull uniform finish ,polish it with cutting compound (G6/7) or t cut.
the only problem with this is if you go at it too hard & break through-its a respray!
the most common prob with older paint is UV rays causing a milky effect, or the laquer breaking down & showing what appear to be tiny scratches.
the above are only stop gaps-once the laquer starts to go its a slippery slope, but if you're patient, you can achieve good results.
if you want a chat then bell me on the mobile no-its on my website.
HTH