OK, apologies. Seems I do get an output from MISO, for some reason I wasn't measuring it before.

I'm running this up on breadboard (the MAX part, not the 89C part), which I'm starting to suspect may be part of my problem. Interestingly if I touch the sclk input of the MAX chip with a piece of wire (not a screwdriver, or similar) touching only the insulation of the wire - I apparently get success - my LED lights, and if I change the code a different (correct) LED lights. Seems like I'm injecting 50 cycle into the clock which seems to make it work, even though my clock scopes out fine.

Time to get out the soldering iron I think...