Interestingly, the idea of a 7750-based Lederer is the new one for me, I only thought they did 5100 versions!!

I believe that the 5100-versions (which I know a little about) were definitely Heuer-produced.

My one (the picture that Jeff posted on a new PVD bracelet, even though I do have the original) is relatively interesting in terms of supporting this account.

It came to me with all of the original materials, which includes the full Heuer instruction booklet (as scanned and published online by Chuck), a dark plastic Heuer box (lined in a pale plastic inner which has a velour-effect), and the Heuer paper box-slip (with the original owners name and address on it). Mine has Heuer on the crown, and nothing on the clasp, none of which is particularly odd (for these), and the caseback is marked with the Heuer model code only.

As far as I know only changes from the Heuer version are the name on the dial, and the absence of other script on the caseback.

I have examined the movement, and my approximate dating would indicate it derives from mid-eighties, just as Heuer was failing. I would think that the 70s estimate may be a little early, but only because it would mean the association lasted several years, and there are (imho) not enough examples out there for this to be the case. I am fairly convinced this association (like the Tourneau one for the same watches) was one of Heuer's desperate moves to keep going as they failed.

So, how I found mine.
I collect 5100s, and I had seen one of Chuck's references to the Lederer (on its own, without any association with Heuer), and searched hard for this rare beast (It took a while as I had also seen mis-spelled references like Leader). Eventually I came across one of Chuck's online photo directories, and he had photos of Lederers, which I recall included different colours to the black PVD which I have (green and silver, from memory, just as Tourneau did). They certainly looked like they were photos of his own watches. He also had photos online of his own Tourneau range, which was similarly complete. These were not photos associated with any of his articles, but I assume that they were where he stored photos for posting on fora, rather than using a photobucket account or similar.

These photos no longer arrive in any searches, so I can only assume his picture directories are not necessarily within the online resource available to us now (Jeff - do you know if this is the case, or whether my searching is just not spotting them?).
I never accessed his pictures via his site (which has no link to them), only via search results, which regularly came up with them. Not any more.

This is the only other reference I have found to the Lederer's, and I have only ever seen my one for sale (which cost me $400 on a Buy-it-Now on Ebay). I too would welcome any further insight into these.

I would also point out that the Tourneau versions are much more widely seen, and are similarly Heuer-made (the only difference being that it seems many Tourneau's do not have Heuer on the crown).

I also assume that Lederer itself is now Lederer de Paris (see www.LedererdeParis.com), as the script is identical, but this may be a mistake. If I am right, they do not do watches any more.

Not sure, but I hope this helps. In the meantime here's another photo of mine on its original bracelet

Cheers
Dave