Someone with actual skills doing the stem replacement, like George.
(insert big thumbs-up here) But...I see disastrous pipe restorations on ebay all the time, where people who want the pipe to be something it isn't (like 1/4" NOT expertly taken off the top), pay top dollar. Fools are parted from their money all the time.
These two items are not British pipes, but the Peterson Patent tools are 'British Made', and the Dunhill reamers are made in Austria by a British company. I 'had to have' a Patent tool and the Dunhill reamers were irresistible for reasons I can't explain.
2x PETERSON'S PATENT FOLDING PIPE CLEANING TOOLS c1910 | eBay - https://www.ebay.com/itm/175623494397
2 Vintage Dunhill Carbon Cutter Pipe Reamer Made in Austria Original Pouch 1, 3 | eBay - https://www.ebay.com/itm/364167837027