Hi Brian, Just cruising around and saw this question. I use 1.25 flexible exhaust hose that is made by Walker auto. I buy it from a distributer called Rock Auto. It comes in a 20 foot roll, about $40.00. I am sure you can find a source for it in England too. Great stuff. It will rust if left out in the weather but it is cheap and works very well.
Source: William (firstname.lastname@example.org)
Here's links for Walker Flex Pipe: (scroll 1/2 down)
Feedback (MP): WALKER Part # 40001 More Info 1 1/4" ID- 1 3/8" OD, 25' OAL FLEXIBLE TUBING--Plain Steel, $1.52/ft, 9/12. Good delivery. A 1” nipple will essentially “screw-in” to this pipe. Not an airtight seal, but close. With some high temp sealant, may be airtight, and sealant may last, depending on how close to the engine the connection is.