So I went in search of a core from a solar inverter (this was a Clenergy 5Kw jobbie) so
Ripped it open and removed the transformer block (this was a rubber encapsulated block) and this looked promising (turns out this was three separate blocks that looked like one-so how to remove the rubber
Well Acetone effects most rubbers so soaked it in that for 3-5mins
and it peeled off pretty easily - BUT NO FERRITE - BUGGER! - Just three iron cores -The search continues ;thinking microwave oven inverter power supplies (so if you have any old 1200w ones and can part with the power supply board let me know)