I too am on a "running break" as I turned my ankle over and sprained it 9 days ago ... It's actually recovering very quickly though and though I'd written off the rest of the year I think I may get a few runs in between Christmas and New Year.
I think you're probably right on the HM front - my mileage is up and has averaged over 25 miles a week since the middle of March, but my longest run (ever) is still only about 14 miles - I think a bit more over-distance training would really help the HM endurance.
Impressed with your 5k and 10k times - well done The statistician in me can't help but wonder your age and hence the Age Grades of those two PBs. All my current PBs, except the HM set a few days before my birthday, are at age 48 giving AGs of a little over 75% at all events.
And more specifically on topic, I've done 5 more 10k races since my last post and recorded 2 PBs there too:
15/6/13 - Battersea Park - 40:34
17/11/13 - Brighton - 39:33!
Like you, Strangely and Iwan, I've also improved my HM (29/9/13 - Ealing), but only to 1:29:53. You guys seem to be doing even better over the longer distances. Meanwhile I've been trying out some shorter ones and recorded a 2:25.9 track 800m on 4/12/13 which, by age grade, is better than all my existing PBs despite that being only the second 800m I'd run. If I can find the opportunities I'm going to focus on getting the best 800m, 1500m and mile times I can on track next year. Again if I get the opportunity it'd be nice to try for fast 5000m and 10000m times on track too.
Meanwhile, back on topic, 10k goal for 2014 has to be sub 39:00