I have a Singer 15K80 (fixed feed dogs and no reverse) which left Kilbowie wearing a serial number allocated in 1957!

That late! I have come across a few cases like that on the web. I wonder why Singer kept the old version in production, there must have been a reason. Both 99 and 66 were given a simple reverse function too.

21st April 1932 - first run of 201's in the US, produced here until 1957. To narrow down when exactly when the 15 began to have that same reverse lever in the States, we'd need to have a look at as many 15's as we could with serial numbers beginning with the prefix AC & AD. =)

I need to rephrase that. Although it is true that the singer 201 made it's debut in 1932... the potted motor model 15 (unsure if this would be a 15-90 or 15-91) had been out since at least 1930. What's really interesting... is that while the 1930 15-91 had the same reverse/forward lever as the later 201's... the regular old 15 with an external electric motor and belt drive continued to have a lever much like the one in the OP's photo up until at least 1937. I'm still at a loss to discover when exactly the belt driven 15's were given the 91 type lever.

Interesting info Steelsewing. I have not been able to get accurate details on the introducition of the 201. The earliest date I have read is 1928, but some give 1930 as a date too. I guess there were a few years of development, test productions, I just have to note down the best ducumentation when I come across it. There were definitely many years of overlapping in production of the various version of 15 and other models. I have come across late 28s too, with serial numbers dating production to more than a decade after the 128 arrived.

I'll be the first to admit that I was perhaps somewhat narrow in the search. I began checking casting dates. In particular the late 1920's and early 1930's, and went off the AC and AD lists only. I probably should have looked at other letter codes to verify. Then, for fun (?) I checked online auctions for photo and descriptions of 15's, and tried to keep on this side of the pond. So the findings may be flawed. The production dates on the 101 probably hampered this since it was a US only machine and the 201 supposedly replaced it. If the 201 is being made in 1932, then it took Singer several years to 'replace' the 101 as both appear to have been being built concurrently for several years. As helpful as casting dates are... they don't differentiate a run of 15's from a run of 15's, leaving all sorts of room for speculation.

There is a page with 201 info, it is written by a guy who has gathered a lot of info on old sewing machines and has worked with the for years. He has most details on the Kilbowie factory. I don't know where he found the information. From a quick search on serial number lits, the earliest UK production I could find was 1934. This is from his 201 page;