Diff Oil is running down from the bottom of the hub down the tyre & pooling..
It's the pffside hub & has contaminated the brake shoes too

2 questions - is it likely to be the hub oil seal (I take it that's a yes!!) & 2nd question is how do I go about replacing it (or can I just tighten up a hub nut or something??)! Car is a 67 F reg 1098 with the newer diff with filler hole on the back.
On checking the oil level in the diff it had lost about 10mm in 2-3 weeks so not too bad yet but will only get worse obviously!
Cleaned all the oil out tonight & had a brief inspection couldn't find an obvious way to check the hub nut was tight (in fact I couldn't find a hub nut as the bit I thought was a cover didn't seem to be...). One thing I did notice was that if I turned the hub backwards & forwards there seemed to be some backlash there, does this suggest anything or is it normal??
Cheers!