As the others have said its probably either rubbing back plate or something to do with the shoes etc. otherwise it'll be the bearing.
surely a squeal isn't the same as a grinding sound? if indeed it's a squeal then i'd check bearing, you must have done 500 plus miles since the brakes were done and usually the noise would be instant if they didn't match, it certainly made no noise when i've been with you, check the adjusters or the handbrake as birdy suggests but as you know yourself jack it up and spin it manually and you'll soon see, alternatively you are in this instance allowed to use my patented repair "radio up another 3 notches"
I admit to have used that method a few times but it's a little embarrassing when driving through a quiet village or arriving at a show accompanied by a very loud squeak squeak
