I have the same problem too! (Being tall that is). I'm 6' 1" with an inside-leg of 36" and I was having to live in a pair of stretchy drawstring trousers that I normally wear. It was driving me mad!
But I've found a website that does extra-long maternity trousers and tops in the UK. It's called Beanpole Bumps (
www.beanpolebumps.co.uk) and they do trousers from 34" to 37" - I've got some of their jeans and black trousers and they're really comfy. I was starting to panic that I wouldn't have any work trousers and can't really get away with crop maternity trousers for work.
I sympathise too with those with the other problem of not finding short enough/proportional maternity clothes. My friend is 5' and she had terrible trouble and had to take everything up. How come it's so hard to get a range of sizes in maternity clothes??