Aye, I am fitter now and can run for longer (even with the extra weight) so will hold on to that.  Thanks.

As an interesting point, a friend of mine who has done a lot of gym training came out with me trail running a few weeks ago. Now, he's 2 stone lighter than me, and a lot fitter, and yet was struggling a lot with the difference in terrain, etc. For 3 days after the run, he described his lats/obliques as 'agony' and couldn't do any gym work at all. Fast forward to now, a few more trail runs later, and he's put on about 4 lbs, and is keeping up with me.

His view : he's been so used to a controlled landing platform in the gym, that his core muscles weren't getting any real use on a treadmill. He's not changed his training or diet at all, (put in 7 miles trail, taken out 7 miles in the gym) that the only way he can see it is that the weight gain is from building core muscles.

So no, weight gain isn't all bad.

Hi Darren.  Have you managed to keep up your lunchtime jogs?  Yes, this weight maintenance or loss is not easy even when we run - it seems to be a matter of getting used to eating the right amount to suit your lifestyle and how much you exercise, and then if that changes it can be a problem.