I find Dolphin Glaze does 'kick' very quickly, so you have to work fast with it, and only mix small quantities at a time. i sometimes mix a little with the Fantastic to get an inbetween consistency and that works very well for me.
Regarding fairy power spray, I've seen this recommended a few times on this forum, haven't used that exact product myself, but used similar products based on oven cleaners (Mr Muscle etc.). They're all a fairly diluted mix of caustic soda based chemicals, very good at removing oil based paints like your Humbrols etc. Not so good for tougher coatings like cellulose and lexan paints, and probably won't touch anything two-pack based, which are essentially resins. I do find it helps if you rub the paint down a little first, and you do need to leave it on for a while to do its work.
A stronger caustic solution would work better, and the chemicals can be purchased cheaply from ebay etc.
But it requires care when using this stuff, incorrect use can result in splashes, and this stuff attacks skin, flesh and eyes with tenacity. So be careful.