I belong to the Teignbridge Trotters who organise the Teignbridge 10 and will be marshalling this Sunday.
What is it like? It starts and finishes at the school grounds in Kingsteignton, Nr Newton Abbot, around their playing field. But then it's all mainly flattish, quiet country roads, following a repeat loop of approx. 4 miles before entering the aforementioned playing fields via a housing estate to finish. There are usually a couple of hundred runners, making it a very social event. If you're looking for a fast time then this is the one (I think it's just under 10 miles!).
I wouldn't want to unduly worry you Neil but I strongly suggest (as others do) that you visit your GP. More specifically request having a resting ECG or stress treadmill test. Your chest pain symptom can be indicative of a heart problem and angina type pain. Last autumn I started having chest pains whilst out running, eventually the pain spreading to the left shoulder and around the biceps. I thought it was a problem with the rotary cuff or some other tendon problem in the shoulder. Or perhaps a trapped nerve or whatever. It was the exertion of running (the pounding, etc) that triggered the pains, unlike cycling where I experienced little discomfort and was able to continue for many miles with this particular activity.
After several months of experiencing this acute chest/shoulder pain, and the onset occuring exponentially with diminishing effort tolerance, I decided enough was enough and had it medically checked out. Xrays and scans on the shoulder area revealed nothing remarkable was happening. However, this was followed by a resting ECG, identifying an abnormal heart rhythm. This culminated in an emergency hospital admission and having a metal stent fitted due to a blocked coronary artery.
In the light of this experience my advice to all runners is to promptly get the pain checked out with your GP. If this isn't convenient and the pain persists then go directly to your local A & E Dept. no matter how foolish you might feel. It is just worth doing even if a heart problem isn't diagnosed. You don't mention your age Neil but if you're over 50 then you're in a group at greater risk of heart problems no matter how long you've been running.
I tried to get advice on the runner's world forum at the time of having these worrying pains and no where could I find comments that connected my left shoulder pain to having possible angina and heart problems. There was nothing indicated that the pain was referred from the heart. Also I thought the pain would never go, the problem dragging on as it did indefinitely. That's really why I'm posting this now to alert fellow runners because remedying the problem has given me a new lease of life. It was sheer bliss not experiencing the pain anymore and to run normally again. Granted I had to routinely attend rehab sessions for several months after hospital discharge but this was a small price to pay.
Having said all the above there's probably an innocuous explanation for your chest pain.