The modern Onoto company is a name only. The current company bought the name from a holding company and is manufacturing under that name. De La Rue has long since passed and Onoto went that way in the fifties if I am not mistaken.
De La Rue is still a massive company, specialising in security printing (banknotes, passports, credit cards, you name it) : http://www.delarue.com
I think they decided in the fifties that pen manufacturing no longer fitted their portfolio, and that part of the company probably was not worth selling on, so they just closed their pen division.
Here's some fairly extensive info on the Magna: http://www.penpractice.com/page25.html
Some more history from RHR on these boards: http://www.fountainp...3-34-the-onoto/
The new company, although not related to De La Rue does at least try to emulate the quality of the original pens, and their decision to produce plunger fillers (however limited) is to be applauded - other companies wouldn't have bothered with the hassle of design and servicing that those sorts of pen require. There is also a definitive History Of The Onoto currently being written by Steve Hull, which was going to be published in time for last autumn's London Pen Show, but I'm guessing it wasn't finished in time. I presume publication is imminent.