I ended up using this giant 3 jaw puller. It quite easily did the job.
I had to stop the hub from turning by attaching a set of multi grips to the puller, but once I did that and tightened it up the spline came straight out.
Reason for it being so stuck was a bit of rust. What do you guys recommend I use for cleaning up the parts and getting the rust off? And what type of grease should I apply to the shaft before I put it back in?
Thanks in advance.