Thanks all for the quick replies :-)

I forgot to say that I did dip the derailleurs in hot water (well, water tank hot, not almost boiling hot) and eco friendly degreaser (Oil Eater AOD1G35437 Cleaner Degreaser 1 gallon from Amazon). That didn't help. Mind you, I might have not left it long enough for it to take effect.

There is no quicklink on the chain so I'll use my Filzer Chain Cleaner with mineral spirit and see if that works.

Thanks again.