Was chatting to Nest about their latest OT offering and they tested a Dutch boiler brand initially years ago finding it 'woeful' in modulating itself according to the OT but as the boilers have evolved so performance (I write performance as I don't know about compliance) has greatly improved. I wonder whether it can be the same manufacturer and I hold no torch for them particularly, just repeating a conversation. It was also reported recently that Nest OT doesn't modulate the boiler, stated on their webpage apparently, just turns the boiler on or off by the protocol. Haven't heard anymore on this.