In an attempt to affect a temporary repair I have applied an exhaust cement to a broken exhaust. The instructions said to leave the bike idle for 20 minutes after application, now I know this is not generally recommended for K's but since I only plan for it to be a one off what could possibly go wrong...????

Well returning to the bike after 12-15 minutes there is a puddle of oil under the bike, dripping from the exhaust collector box. Switched off engine and leaking stopped.

From my limited knowledge/experience I suspect it is gearbox oil. Can anyone offer a possible explanation is to what happened and maybe why?

Dripping out from the exhaust collector box...

Condensation inside the exhaust, dripping out. we used to get that badly on the old Honda 4s, ticking over the drain hole would be dripping for quite a while because on tickover the exhaust silencer itself does not get very warm and ends up full of condensation. Smells fairly crap.

From the exhaust collector box the only way in, [assuming its coming out from it and not off it] is via combustion. When you fire up a K that's been idle for a while its burning all sorts of stuff including some oil and it all condenses inside the silencer. Add some pre existing condensation and that Holts stuff you are using then it may well all be harmless.

If the oil is coming off the collector box check the top side of the engine. I am not familiar with how the 16V exhaust is configured but one possibility might be the crank case very pipe but you would see that on top of the engine around the coils. That would be engine rather than gearbox oil. Other would be coming from rear of gear box but I don't know enough about 16V.

Is the oil dark or light(clear)?
Was the engine running on the centre stand or the sidestand?

Is it dripping from the gear lever? Gearbox oil really stinks compared to engine oil, so you would be able to pick the difference