I had a small leak from a small hole in the expansion. While cleaning off all the old paint and scraping at various rusty areas more holes have appeared so it looks a bit moth hole ridden. I am not sure that it would sensible to get the holes patched over. The question is are there replacements available.
Thanks, Paul
For interest – my car has a stainless steel header tank that I bought from David Beales about 40y ago. I doubt they’re still available, I think he just had a small batch made up at the time