Them's the one's Cavey.
or an alternative
Prop shaft does not rotate. The whole lot has got no feel.When you spin the wheel look at the front prop shaft, is it turning or not ? Just because both front wheels spin does not mean that the front diff is the problem, it may be but when diffs go there is usually a rough/crunching feel to them.
Wot he said^^^^^It's not normally that tight, you should be able to "tap" it off with a screwdriver or drift.
Tool 606435 (part # BA3039) is around £8 on eBay - search for Defender Wheel Bearing Hub Nut Box Spanner