How much mayo is too much mayo ?

That's very normal, in fact that's better than most!

From the colour of it i'd say its had pretty regular oil changes?

Great - thanks all - appreciated :-)

Looks reet to me. To be fair these engines suffer more with timing chain cover gasket failure causing heavy oil emulsification and loss of coolant, resulting in timing chain and bottom end wear. Also the sump strainers block with carbon causing the timing chain and bottom end to wear, as well as the oil filter collapse and disintegrate to the same effect. The chains do also just wear, and I've had a few suffer failed hydraulic lifters and the oil pressure switches and timing end crank oil seals fail causing heavy oil leaks and the oil pressure switch failure causes oil to be forced up the wiring loom and into the ecu causing ecu failure unless the rubber seal in the oil switch plug is removed.
Not trying to be a doom monger, if you clean the sump pickup and keep on top of oil changes and fit a new OPS they ain't too bad.