I remember this series with great fondness. Together with the likes of GBH, North Square was produced by Channel Four. Unlike AB's series, it could have been continued and was cancelled because of some damned fools, choosing that they didn't want such dramas, (termed as being too American at the time) on their channel. As has been said, it could have been budgetary concerns, but whatever the reason North Square remains one of the best series C4 ever produced.
Look at the cast and people behind the series. People who are now household names started on NS and the quality shines through every episode. In fact, series like Silk probably wouldn't exiist without NS. So, if you like quality legal dramas, fine acting, great plots, etc. buy this series. If only they'd stuck with it, I'm sure it could have run for years. As it is, it goes down with other missed opportunities, foiled by the people who went on to make Big Brother and Coach Trip.