That explains it then Rob... I am assuming the end/nose of the flexy is flat. If that might be the case then you could damage the threads with any material removal if not done carefully. Also you would not wish to get any filings inside the flexy pipe to later find their way on to brake seals, thus the two washer system seems a reasonable bodge..?
Yes, thank you for confirming, I'm very reluctant to start filing away, it is a flat end - it's taken me almost 50 feet of brake pipe to get one 4 ft length I'm happy with, so I'm not looking for more rabbit holes to dive down if I can help it :-). Plus the whole concern with fillings ...
I'll try the double washer.
Thanks for the suggestions - there was a copper washer on there previously so I assumed it would need one for the new fitting - perhaps not. The union and the brake pipes are both new from New England Morgan Spares so I'd be disappointed if this was a compatibility issue. Definitely a significant leak (so probably more than a thread sealant should be used for). Back to the drawing board for now.
I did notice that in this
diagram on their site there does appear to be a washer - no. 39 but it's not labeled so I'll see if they can shed light on what I should be using here.
so there is…we learn something every day. So it’s now an issue as to whether it’s the correct sized washer or… I notice that part 36 looks to be a flexible rubber pipe. Is that what you have or are you trying to mate a solid pipe to the tee piece??
it is a flexible rubber pipe, I'm not trying to make any more solid pipe than I need to - that's been an exercise in patience and fortitude !
Sospan, thanks for the link. I'm going to be back in the UK next month - time to figure out what i need to stock up on in terms of car parts .
The list of people willing to get in to the car with me is definitely in single figures at this point

.
Ok, off to break something else ...