Sounds like the Imperial Defense mags that were floating around in the early 2000s. When new they had a sticker on the magazines that said 'England". Otherwise, they were just very plain in appearance with a gray parkerized type finish similar in color to what is found on a USGI aluminum mag. Some had Imperial Defense stamped on the floorplate. But some did not. I think I still have a few of these mags stashed away somewhere if I can manage to find them. If I do, I'll let you know if the "number 2 inside a circle" marking is on them.
From what I remember, these are actually very robust magazines, at least as far as the bodies go. But I think the springs in them were a bit weak. I've heard of people changing out the springs and followers in them and reporting good results. These mags are also considered pre-ban.
Here's a side view of what the mags look like from an image I pulled off the web:
I also seem to recall that some of these magazines also had a darker park type finish, almost black. But my memory is a bit fuzzy. I may be confusing a different brand of magazine with these. And they have plastic followers as well, which are kind of cheap and crappy looking compared to something like a Magpul follower. I wish I could be a bit more helpful, but it has been forever since I bought these things...probably in the 2001/2002 time frame. I'm sure they are buried in a box somewhere in the bottom of one of my closets among other magazines hoarded during this time period. Still, I'll make an effort to find them to check the markings for you.