Seems I've certainly done something to my left calf. Can't quite tell if its soleus or achilles tendon. Either way its ice and rest for a few days at least. First 500m it felt fine then a little bit more tightness started to creep in eventually getting worse to the point of having to say to myself 'time to walk'. I've had heaps of soreness and perhaps niggles this year, but I think this is my first real injury.
I put it down to a combination of sore/tight calves following Mt Solitary, running in racing flats and probably going a bit too hard on a few runs post Mt Solitary.