Does anyone know if the coolant by pass hose is entirely necessary on a 1.8 Silvertop Zetec installation. I'm asking this as I can't use the standard thermostat housing because I'm using an MX 5 gearbox and I've had to cut the bottom off the housing with the bypass hose connection to clear the bellhousing. From what I understand Ford use the bypass hose to speed up warming of the engine. Does anyone have experience of running without the bypass?

It will need some sort of bypass. You may get away with a 3-5mm hole in the thermostat, or you could fit a remote thermostat with additional bypass fitted.
Something like this https://www.carbuilder.com/images/thumbs/002/0028559_by-pass-thermostat-87-degree.jpeg

That looks a handy piece of kit, but there appears to be no means of replacing the thermostat if needs be. I'll put it on my list of options. Ta!

There are several types available, landrover, MGF and many others. Some are not expensive, you replace the whole thing if it fails

Without a bypass the coolant won't circulate properly within the engine when the 'stat is closed. That can cause hotspots and uneven expansion. That was the cause of most head gasket failures in early Rover K-series.

Good point, so I definitely need to sort out a bypass. Thanks for the heads up.