Anyone know of such a beast?  I want one.

Any details you can provide would be most appreciated, even if it's where to find parts kits, magazines, semi-auto parts, etc.

Thank you!

There was a semi-auto version imported into the US back in the 80's.  The importer was Cassi, Inc in Colorado Springs, CO.

This was the Sterling MK 6, made by Sterling Armament of London, closed-bolt, floating firing pin fired, with a 16" barrel and a folding stock.

Importation stopped around 1990 when Cassi went out of business and not that many were ever imported due to the high cost.

I don't remember seeing any parts kits, and I don't know of any sources of spare parts.

There's a semi-auto copy made by PAWS.  Here's one with a phony silencer:
http://www.gunbroker.com/Auction/ViewItem.asp?Item=45162435  

Here's some build it yourself tubes:
http://www.gunbroker.com/Auction/ViewItem.asp?Item=45431156
http://www.gunbroker.com/Auction/ViewItem.asp?Item=45431187
http://www.gunbroker.com/Auction/ViewItem.asp?Item=45431211

Here's a PAWS pistol:
http://www.gunbroker.com/Auction/ViewItem.asp?Item=45423423

Here's a real SMG.....Hold on to your wallet:
http://www.gunsamerica.com/guns/976674012.htm

Hrmmm...

What's the report on the quality of the PAWS stuff?

Stay away.  My department used some of their full-auto subguns many years ago, and reliability was spotty at best.  I've had Bob at PAWS do a little work for me (once), and it was not that great.