Deciphering James Upshall/Tilshead Shank Markings

Close to 30 years ago, I acquired a pipe made at the James Upshall pipe works. The pipe is a straight/saddle stemmed pot, with a 2" diameter bowl X 1/3/4" high...OAL about 6-3/8" Wall thickness at the widest diameter about 1/2" tapering internally towards the top rim which is 3/8" thick at the top of the 1" diam smoke hole...which is flat across the rim. It's a nice pipe, but I hardly smoked it over the years, and the pipe lived in my drawer until recently. I decided to start smoking it again after all these years. It's much too heavy to clench, so for me, it's a living-room pipe. The pipe actually looks heavy/chunky and a bit larger than usual pots. On a scale of 1-10 I'd give it a 5. Not my favorite pipe, but I don't exactly hate it either. I could live with it.
The left side of the straight shank has a "James Upshall" logo stamped inside an elongated oval border, a "white JU inside a white circular emblem/mark on the Vulcanite stem and next to the shank logo, are the letters "DS EXL". Stamped into the other side of the shank..."TILSHEAD England, Made By Hand". The pipe has fairly nice wood with some areas around the bowl showing straight grain, no flaws, no sand pits, no blemishes.
Can you J. UPSHALL lovers decipher the shank designations/stampings? What do the coded letters signify, quality-wise? Why the "Tilshead" designation if it has a James Upshall logo stamped on the shank. I read that Tilshead was considered a "second" the Upshall grading standards. I remember paying close to $200.00 bucks for this pipe back in the late-'80s early-90s. I no longer have the original paperwork/receipts.
I'm a pipe user, and not a pipe trader/collector. I am not squeamish or reluctant to re-work any pipe to conform to my likings. So, I did just that. I decided after all this time, to revamp this old pot. It was easy. I held the straight stem over a lit candle, to heat/soften the stem and gave it a very slight bend (1/16th bend)... and then I sanded the top, outboard edges of the flat bowl rim and rounded off way the too severe, sharp corners of flat top/rim. Now the pipe looks much better, to me. It no longer looks like a briar toilet bowl with the seat up. A good sanding with for the rounded over rim edges, with 400/600/1000/1500 grit paper did the trick. The old TILSHEAD has a smooth-as-a-baby's-ass feel to the wood now, and the freshly bent stem is slightly more confrontational. If the pipe looked like it does now, 30 years ago, it would have been a well-smoked hunk of briar. Now, the pipe has come out of retirement. Smoke rings will once again rise from the revamped bowl....as intended.
Frank

Thanks for the interest, and education regarding my Tilshead pipe. Also thanks for providing the interesting links. Really appreciate learning some the answers to my queries. Finally, after 30 years, I know about the pipe I own.
This subject: my Tilshead pipe, came to be owned by me in a very convoluted way. It all began about 30 yrs ago as I was shopping one day in a Westchester, NY mall, called The Galleria, in White Plains. I stopped in a pipe/cigarette shop and in a glass case was a gigantic, James Upshall 1/4 bent Dublin...a perfect straight-grain, and it was for sale. It called my name. At the time, for me- the asking price for this jumbo pipe was obscene, but I bought the pipe anyway. However, after smoking one or two full bowls of tobacco, cracks started to develop on the interior walls of the smoke chamber. I was absolutely crushed. I contacted the pipe shop and returned the pipe for a refund. No refund was offered....I could only get a replacement of equal value from James Upshall. I waited for months for my replacement pipe to be made, and I finally got a call from a Mr. B.Siegel -who ran a place called "Marble Arch Ltd", located: Rockville Center, Long Island, NY. I'm only guessing that Marble Arch Ltd. was the importer/distributor for James Upshall pipes. He said to come in....that my replacement pipe was delivered... So, I went.
Anyway, the much anticipated, replacement pipe, looked/was nothing like the original pipe that had developed the cracked bowl. Upshall Pipes/Siegel really tried to make me happy, but in the end, I was still crushed, the replacement pipe that was offered was no substitute for the original, it never called my name, and I was out a lot of money as far as I was concerned, but, in the end, I thanked Mr. Siegel for all his help, and walked out of Marble Arch, with a pipe I hated. Long story short, I eventually traded that still new-in-th-box, Upshall replacement pipe for an over-sized, smooth, Tilshead pot, that is now the subject of this thread.
Sorry for the rambling story. I remember these events as if they happened yesterday. So now after almost 30 years, I finally learned how to enjoy my Tilshead briar...but only after I reworked the bowl. The end.
Frank