Jaz That suggests it's a 73 model and not a 74. The early handles attach completely differently to the 74+ handles, which use a screw.
The 73 handles have a clip which holds them onto the window winder spindle stub. To remove them, you slide the big huge plastic/bakelite washer to disengage the clip. I have the handles and the big washers, but I don't have any spare clips or the other metal washers which sit underneath, or the springs.
From the parts diagram - Drawing 15149 from the 164 parts manual (same as 140 here) Group 8, Page 34, pdf page 482.

I have [42] / [43] / [44] / [45] / [46] as complete handles, and the big plastic washers [47].
You will need to get these from somewhere else -
- (clip) spring [48] 687299-8
- (metal) washer [49] 676215-7
- spring [50] 659949 -2