Just had a look in the electrical cabinet. Inside there was a full schematic on a bit of paper folded up in the bottom! (its basically the same as what I posted above)

Looks like is has the Star-Delta start and braking (which is DC across the motor right?)

I doubt a VFD will like any of that, so will need to bypass it and wire the VFD direct to the main and Delta outputs of the start contactors (assuming I go for a 220v - 220v VFD)