Almost but not quite, Buffdog.
I was shown serial number 04 of the 4.85mm X-70 rifle. This was 3 days after the first photograph (left side only: right side told you too much) had been released. The rifle itself still was rather high on the "Secret" list. We played with it, right in the Pattern Room, for about half an hour, tearing it down completely. I got a VERY good look at the internals of the rifle as it existed at that time. When all of this was done, I was asked if I had any recommendations. I thought about it for a couple of minutes and made 3 suggestions.
One suggestion was for the use of light alloys, the rifle I was shown being entirely steel construction. This, I found out, had been tried and rejected for one very important reason: they had learned the lessons of 1940 well. To build the rifle in England, NOTHING need be imported; the entire thing is built of LOCAL materials. If Britain is caught off-guard again, at least they can build their own rifles.
The final suggestion regarded training and operation, the rifle being at that time a dedicated right-hand model. This is when I made the suggestions regarding mirror cuts in the frame, repositionable extractor and ejector, mirror-image ejection-port cover and bolt-handle cuts in the Carrier, to enable fast swapping of parts to create a left-handed rifle on a minute's notice OR a combination L/R rifle for dominant eye and special-purposes uses (firing around corners, etc.).
They noted this down carefully, I inspected Maxim Guns for the next 3 hours (they had Serial Number 1 on one table, Serial Number 100 sitting on the table next to it! Number 1 was unmodified, 100 had ALL the mods approved before the type went out of Service: a treasure-trove of information in those 2 guns!). Came back to Canada, heard no more about it, although I did arrange a swap with Peter Labbett for a 4.85mm round, likely the first one in Canada in civilian hands. Few years later a new edition of Small Arms of the World appeared and there were MY 1-1/2 lines: they had built the conversion units, they had worked.... but had been axed by the bean-counters.
So, as it stands, I own 1-1/2 lines of Small Arms of the World, Sir Charles Ross has a page, James Paris Lee has about 5 pages: the World is well in proportion!
But I really wonder why nobody has done it. About 1 man in 7 is born left-hand dedicated. MOST of them are converted (with difficulty ranging from little to extreme) to Right-hand over time but (1) a small hard core exists of men who can NOT be converted and (2) they STILL will be more adept with Left-handed rifles and tools AND have a lower accident rate "on the job". Add to this that the proportion seems higher among Women (which could be due to social tolerance) AND the fact that it now seems socially-acceptable to send the honeys In Harm's Way, this after we have spent 4,000,000 years trying to protect them. To me, if making our fighting men and women safer costs an extra $10 on a $1500 rifle, go ahead and spend the damned money!
Rifles cost dollars; blood is beyond value.
Someone with a very big stick should pound this into the heads of the damned bean-counters.