The thing with any brakes drum or disc is that the friction material needs to be bedding in,if you use your new brakes really hard from the word go the surface will glaze,hence you will not get the full brake performance as a result. The trick is to treat them gently with nice progressive braking from the go.

Also whilst you have the brakes apart it's a good time to check that no cylinders have sticky pistons,being careful not to eject them right out, also to have a look at the state of your fluid in particular in a system with normal brake fluid. Letting some out of the bleed nipple having pushed the piston right back, is a good indication of the business ends state.If it's shitty then a fluid change is in order...

Update: It looks like I've got a leaking front right cylinder.

sounds like its an overhaul job johno

Finally got around to sorting this yesterday. As guessed, it was a leaky o/s cylinder. All now done and back together, with new shoes, and working well. Thanks to Aidan for help bleeding and loan of a couple of tools.

Apart from being covered in Dot 4, the shoes were still perfectly fine, and would have had plenty of life left in them. They'd been on for 7 years, and this is my main-use car. I've also taken it around Scandinavia and to the French Alps/Czech Republic etc. in that time. I guess I don't use my brakes very much.