I bought the Regal Queen for my wife as a Christmas gift and was disappointed that no converter or cartridge came with it. I ordered the converter from Goulet Pens that was suggested in this thread and tried it. It does fit snugly in the feed, but the handle of the plunger does not fit when the converter is filled. When screwing the body back on it pushes the plunger down, thus pushing out the ink. I have looked inside to see if there is something stuck up in there and it is empty. While the pen is a nice looking pen, I will be very cautious of Regal brand in the future. I am not comfortable in giving it to my wife now because nothing fits in it, this pen is going to end up being a dip pen at best. I know some are hacking some converters/cartridges to fit, but I think that if you are buying a pen that is made recently then it should come ready to write with one form of ink storage or the other. I expect it with some vintage pens, but not this.
Follow up. My wife loves the pen and the smoothness of the nib after I gave it a few strokes across the tuning paper you get from Goulet Pens (can't remember the technical name at the moment.) I previously complained about not having a converter. I ordered one that was supposed to fit, but it didn't. So I would refill a cartridge with my wife's choice of ink. Then one day while cleaning it, I felt something finally move in the barrel. Keep in mind I had tapped this thing a lot to see if something was jammed in there. Well this time a cartridge came out. What looks like happened is the cartridge was put in there had a leak and the ink acted as an adhesive and a seal. After being carried around and used by my wife it came loose. The cartridge that came out was covered with ink. I cleaned out the barrel and tried the converter from Goulet, it worked perfectly. All in all this is now one of my wife's every day carry pens. She totes around 6 filled pens, each with a different ink, in her purse at any given tume.