I can now confirm the Knockholt sign is not just a replacement but, god forbid, plastic. It does mean they still have the original font set if anyone needs it, but they didn't make signs out of plastic! It's off my list now as that's not an authentic material.
I went out to have a look at this yesterday and took some more pictures. (I recommend opening them up full size to see what I'm talking about properly.)
I don't believe this is a repair job. I think the panels are original, and have been looked after; for whatever reason the rest of the sign face hasn't had the same good treatment.
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The letters are as DavidNW9 described: not embossed or cast like very old PW signs, and not heat-treated vinyl overlays like modern signs. However, I have seen other signs made this way before - it looks like they've been screen printed to me. In this picture you can see small scratches that have lifted off some of the ink, showing white underneath. I remember growing up, when signs on council estates in Leeds were all pre-Worboys, saying things like "No Ball Games By Order", seemed to be made the same way. I remember scratching them with my fingernails to see if the lettering would scratch off. (It didn't.)
The panel is not metal, as evidenced by the small cracks appearing at the corners where the rivets have been driven through it. Sheet metal wouldn't do this, but some sort of plastic would.
You can see that the whole sign face has undergone some degree of maintenance: the surround has, at several times in the past, been painted. I doubt that black was its original colour. It has not been painted for some years and it is now flaking away to reveal the sheet metal underneath.
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The arrows are made up of two components - a square block and a triangular arrowhead, separately riveted onto the sign face. They appear to be made of the same material as the white panels with destination text on them, and are affixed using precisely the same rivets. They are the same depth as the destination panels (so all three parts are perfectly level against the sign face). It looks to me like the only difference is that they haven't been maintained to the same level as the main panels.
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This is the reverse of the arrow shown in the previous photo. The first three rivets on the right hold the arrowhead; the next one (forming a diamond shape with the others) holds the square block; the other rivet is one of those holding the destination panel. All the rivets are identical. The rear of the sign face has been painted black at some point in the past. New signs of this type in rural locations weren't regularly painted, certainly not to the rear of the signface.
Having looked for myself, I don't see how the white panels on this sign can be anything but original. If this was a repair or replacement job, there would be signs of the previous panels having been removed; when the new panels were fitted, the chances that it could be done with new rivets that were precisely
the same as the ones used when the sign was manufactured decades earlier are practically zero. Further, the sign face surround has been painted, but not for years - ten years at least, I'd say - and yet the clean white panels have traces of black paint around the edge, so they were in situ when it was last painted. Finally - not shown in the photos, unfortunately - the sign is hanging from mountings that are rusted through, so it would be impossible to take down without cutting through its brackets and impossible to re-mount without fitting new ones. Therefore, if the panels were removed, and new ones riveted in place, it would have to have been done in situ (at a slight angle, in the crook of a road junction, with the sign able to move around slightly on its aged brackets), which seems impractical to the point of impossibility.
I don't know for sure how the sign has come to look this way, but I can offer several theories.
- it has been periodically cleaned, but only the destination panels have had this treatment, allowing the rest of the sign face to deteriorate. Certainly it's had some maintenance - it's been painted at least once - so this isn't at all unlikely.
- the arrowheads are made from (or treated with) a different material that has deteriorated at a faster rate than the destination panels, which gives the illusion that the sign panels are newer.