The one thing that the UK arm of Mabie Todd shied away from for a very long time was making overlay pens. So far as I’m aware, no overlays were made in Britain before World War II. Overlays were always a small part of pen production and it probably made economic sense to share one facility for their production.
I don’t know whether this was a pen produced in America purely for the British market, or whether it was also on sale in the USA. These pens are not rare, though they’re moderately uncommon, and they turn up not all that infrequently in either clipped or clipless versions. Here’s a similar one with no clip and a different engine-turned pattern: http://wp.me/p17T6K-b5
Without a little more information, dating these pens with any exactitude is impossible. Any time between 1920 and 1930 will do, and even a year or two after 1930 doesn’t seem to me to be impossible.
Is there a pattern-book for engine-turning somewhere? It would be nice to put a name to this pattern but it’s beyond me. The pen’s not quite perfect; there’s slight plating loss at top and bottom and on the ball of the clip. There’s also a tiny area of loss where the exposed edge of the section meets the plating, a common area for attack by the harsher inks of long ago. That said, in its red leather (or probably leatherette) box it’s a real stunner.
My guess would be that under the gold lies a Swan Minor No2, one of the most deservedly popular pens of its day. As always, it writes beautifully.