I didn't realise that Harris did a swivel pad, thanks for that I will check it out. The only one I could find was a stanley which swiveled up and down, but not sideways like the one in Dai's photos. 
Groundhog, they do swivel up and down, if you look at the photo you will see a small screw, you take out this screw and the handle pulls off. You need to turn it 90 degrees
They have changed the design a bit from the first one I made.
When you remove the handle you will see two little prongs sticking out of the swivel, cut these off, you will notice that the swivel part has two flat sides, you have to surform, or file flats on the other side before you can fit the handle back at 90 degrees. It may sound complicated but it's a 5 min job.
Once the handle is fitted back on at 90 degrees, it swivels the way we want it too.
Before you can put the screw back in, you need to drill a small hole for it to screw into.
The out side hole on the handle is already there, just need the small hole for it to screw into.
It fits onto the Harris cone, most cones are standard