Well learnt somthing today. Turns old the extra effort put into running up hill on my twice weekly 10k run home from work do not translate into faster times when I run the relatively flat (relatively this is Sheffield). I got a very disappointing 54.50ish today, which is pretty much what I run on the way home....
...so its not the hills its the extra 10 years that mean I'm not sure I'll ever break that 45 minute barrier!