Thanks Andy, I slightly misunderstood the wiring side of things. DPS
confirmed that the cylinder stat used is a Danfoss ITC 100 and that it
does operate on a low voltage which can be fed into the low voltage
rail of the boiler (I also checked the specs on Danfoss' website).

My similar Pandora has volt free contacts.

Interestingly I considered opting for 2 stats to avoid unecessary
cycling but the techie chap at DPS suggested that on a priority system
you would be better off having the boiler fire up asap to bring the
store back up to temperature and therefore 1 stat would be better
suited?

Personally, I would ignore their advice and install two thermostats to
provide better hysteresis. Mine cycles a bit too frequently.

Christian.