The mention of Municipal Trailers jogged my memory so does the name James Walmsley ( a.k.a. “Pugwash”) ring any bells with Tom. Jim Walmsley was in earlier years, I understand, Sales Director at BTC who mainly built 4 in lines. I’m not just sure when Municipal started off at Bamber Bridge but Jim used to call on us in Milnthorpe but I never fancied their product though. IIRC he left Municipal and started flogging , and fitting , supplementary oil filters supposedly to extend oil changes by improving filtration which was alien to my idea of oil changes but I did try a couple on two ■■■■■■■ 220’s but took them off after a while as I had no confidence in the idea ! Cheers Dennis.