Kerry Woollen Mills. https://www.kerrywoollenmills.ie/product-category/tweed-and-fabric/irish-tweed-wool-fabric/ Similar to Magee they do: - Tweed cloth - Upholstery fabric - blanket cloth I've purchased some tweed from them in the past. They're usually pretty quick with delivery. Decent quality tweed, and very reasonably priced.

https://der-rote-faden.de/en/ I found this website. I haven't ordered yet from them so I can't speak for their customer service etc.

@Rory Duffy Thanks. I’ll use the information Benjamin provided and start figuring it out from there.

@Benjamin Thanks for the suggestion. I had actually considered having the front of the waistcoat on an angle similar to the pictures you posted as being a potential third option.