Anyone know if this is a common or even likely fault?

I have a drip drip drip from my bellhousing, pretty sure it is ATF as clutch fluid is not reducing at all and master and slave cylinders are new last november.

I do have some clutch slip which is the second part of the question, I am assuming at the moment that the clutch slip is because of contamination, but despite a few attempts at 'burning' off any oil I am having no luck and it is looking like a gearbox out job for the clutch.
Is it all co-incidence and I haven't set the slave correctly in some way which is causing the slip and the slight leak is nothing to worry about?

I have free play at the top of the clutch pedal so I can only assume it is fully engaged, or should I crack the bleed screw and see the slave is not fully disengaged.

Can't figure out why the oil seal would decide to go on the front, I have checked the breatther and it seems ok at the moment.

Front gearbox oil seal leaks are not nearly as common as the engine crankshaft rear oil seal, though a blocked gearbox breather and an overfilled box could do it. Are you sure it is ATF? is it red in colour?
Sadly, if the clutch is slipping, it is likely to be due to oil contamination, and only a replacement is likely to fix it. Sometimes it is possible to have clutch slip if the rubber hose has perished internally, this can work like a one way valve, and prevent the slave cylinder piston from returning. Similarly if the push rod freeplay at the mastercylinder is non existant, the same thing happens. From you description, oil contamination is by far the most likely cause.

Regards,
Diff

I am 70% sure it is ATF, it's dirty coloured when it comes out from dust etc in bellhousing, but it doesn't feel like engine oil and doesn't smell like it. Apart from no drop in clutch fluid I would have thought it was dot 3.
There was some clutch slip after changing the slave, however it disappeared as soon as I put some free play in the pedal.

I've just popped the wading plug back in and I'll see if I can get decent amount (and also see how much) it is leaking this week. If I manage to get a decent amount of it I can pop an old glove in it and see if it disolves, if so it is ATF.

Clutch is only about 3 years old, but it has probably had a hard life, I've it some stick over the last year and a half at least.

Sounds likely - very easy to change once the box is pulled back. Suggest you also check the condition of the spigot bush as if this is excessively worn it can allow the input shaft to move more than it should and hence would eat the seal. Otherwise wot he said - check for blocked breathers and overfilled gearbox.

Even if it is crankshaft rear oil seal the box is gonna have to come off to change it anyway!

Jon