Had some free time to tinker with the car today, so managed to replace the air filter, no idea how old the current one is, but for piece of mind, out with the old and in with the new!
Same again with the coolant, no idea how old that was. But after refilling the system and 'checking for leaks' (as per the Haynes book of lies), I did in fact find one.
Looks like it's from the water pump to me (though I could be mistaken), not sure if it was there before I changed the coolant, but the old coolant was not as bright as the mixture I replaced it with, so I dare say I hadn't noticed it on the carport floor (which has a nice black stain where my Wolseley used to live).
Any suggestions of how to rectify? I imagine it's a case of removing it and replacing the gasket and seal, but of course if one is to remove it, they might has well renew the whole pump.