Advice needed re HM training pace / race goal

Well I'm just going to go for it then. Train to run a 1:51 and take it really easy on the easy days.

Well a female friend of mine, who is in her late 40s, ran 1:45 half marathon and recently ran 23:30 for 5k. So take that as you will. I think under 1:50 should be possible if you are not too heavy.

oh please, thanks for your input.

As long as you run smart and even split the race I also think you can go sub 1:50. The biggest mistake most runners make in these longer races is going out too hard and then red lining which will cost you chunks of time during the last few miles.

It isn't clear if the "5km park run" was a race or a time trial you did on your own. People invariably run faster in actual races so weight that result accordingly: if that time is from a race then the MacMillan prediction may be optimistic (in general race predictors like MacMillan tend to be optimistic predicting longer race results based on shorter ones, especially for people without a lot of experience at the longer distance). If it was a time trial then that 1:50 prediction is more reliable.