My PB was a modest 32 second improvement on my Brighton Half time in February. It was nonetheless a pb. I think it might improve my runbritain handicap by 0.1 as well. According to the website, to improve it, I needed to improve my half marathon time by about 25 seconds, which I did. I think the actual time I needed to improve by will be dependent on how difficult they consider the Birmingham half to be. I think it was a bit hillier than the other halves I’ve done this year and so hopefully it will be enough.