Mega fast London commuter tyres, Vittoria Voyager Hyper's

[Vantage]

Both sets of tyres infated to 90PSI.

There's the reason your tyres let go.
Myself and a few others on the CyclingUK forum have noticed the Hypers tendency to quickly lose grip without warning on damp paved surfaces, but 90psi is waaaaaaaay too high for those tyres and will definitely contribute to that slippyness.
Myself and the bikes combined weight is around (veeeeery roughly) 180lb and 45psi is enough to keep it rolling nicely. They'll take a lot of punishment at those pressures without pinch flats. Even offroading is fine.

 

[MrGrumpy]

Agree with you but I'm 200lb sans bike so keep the pressures up