Having spent the morning driving around Newcastle looking for a new olive, I discovered that B&Q do then as small as 8mm, halfords had no idea, a visit to my local bike shop yielded a 5mm steel olive for a hydraulic brake system. but nothing smaller or in brass,
I have measured my pipe and its just shy of 5mm, I'm guessing it might be 3/16" in which case my local chandlers (not open today!) may be able to supply a barrel olive in this size.
Unfortunately, it looks as though I will have to take the train to work tomorrow!!
