Ive just started looking for some of these yoo..... got some from new look when was pg with ds 4yrs ago and was bereft when they had to be chucked in the bin as I had worn out the crotch (ds might hv been nearly a year old by that time and dh might have been quite glad as they kind of were a bit too big and were maybe worn as low as a teenage boys jeans by then but they were the most comfortable things ever worn! !!!!)
when I was pg I got some 'sexy boyfriend jeans' <barf at the name> from gap a couple of sizes too big, they were great.
they sat low, right under my bump, and i used the hair elastic trick through the button hole for the last few months of pg. SO comfortable and they lasted really well, I gave them too my sister once I had lost the baby weight and she is still wearing them now two years on.
Couldn't find anything decent in New Look near me and dont' have a matalan... will check out Next.. I'm not keen to buy online as I'm not sure about size - my bum seems to have grown so I think I might need to go up a size but don't want them falling down at this early stage.
Next do really good maternity jeans in all styles. They have quite a few boyfriend styles at the mo. I lived in mine during (and after!) pregnancy and they were a great buy. I also had some brilliant jerseyslouch trousers with a foldover waist band which were Next but via ebay. I don't usually shop there but the great thing about their maternity range is that it's about the same price as their other stuff (rather than trying to rip you off as some other high street maternity ranges do).