He is missing the saddle.so no V to measure but Lathes.co.uk says ML7 parts aren't compatible here. The Gumtree link was the most promising but needed measurement and communication.
You can't hurry this if you are expecting to get a specific original saddle there might only be one every 6 months. It will be cheaper to buy another lathe than custom or new parts. Since almost no lathes ever get separated from their saddle when someone decides to break a lathe and sell the parts there shouldn't be much demand for this part.
As you could do with some local help and advice you need to put out feelers for other technical people near you who are not necessarily making it obvious but may have a lathe and other tools. eg aircraft modellers, car restorers, farmers, agricultural engineers, builders.