This one is tough, but there's something about the text that bothers me.
From the serial number, it dates to ~1965. I looked up another 135.012 in the 22M range, given below. It's a pretty ratty dial, but that gives me some confidence that it's original. As you can see, the text placement on the OP watch looks to be quite a bit higher on the dial. The faint mark beneath the leading "S" might be the previous text, positioned lower.
The "Seamaster" text on the OP watch also appears to exhibit some differences. The loop in the first "e" looks to be more closed, and it has a point on the right hand side. The font might also be a bit heavy.
Then again, there were variations in font over the years. I was hoping to eliminate that by finding an example with a similar serial. Difficult to say, but I suspect a redial, unfortunately.
I still think it’s original. Things weren’t perfect in the 60’s and QC wasn’t what it is today. Look at the overall condition of the watch. These SM600’s tend to hold up pretty well and it doesn’t look like one that’s been trashed and would need a redial.
the font is bang on and even has perfectly aged lume dots at the end of each hour marker. Very few people can reapply lume this well to match a vintage dial and would someone really go to all that effort for a £500 watch?
Still original for me and natural variation explains the slight issues.
I wonder if there will come a day when "refinishing" gets skillful to a point that even experts can't tell a difference.
I wonder if such a day (if it comes) will mark bliss or doom. Safe-queen collectors would probably hate it, but the average-folk would love it I feel.
I think average folk won’t care, most normal people are perfectly happy with decent enough redials.
1:1 (or very close) repros are already available for certain parts of some watches. I don’t hit this ever extending to all males and models as the financial reward simply isn’t there.
I wonder if there will come a day when "refinishing" gets skillful to a point that even experts can't tell a difference.