Thanks also to Stephen, VK2BLQ, who kindly gave me a length of water pipe to mount the antenna on.
The antenna is manufactured from square aluminium tube, welded and with a perspex spacer at the top of the J.
I found that mine was a bit short and have added a sliding section of right angle stock to the end to get it to tune up.
The 6m band is quite wide and it's hard to choose where to tune as I'm interested in both 52.525MHz for FM all the way down to 50.293MHz for WSPR and below for digital modes.
The taps for the stub are attached with U-bolts at the moment for easy adjustment. I'm not confident that the connection will be good after a while in the weather but so far seems fine. Peter also supplied some stainless steel long bolts and nuts that I'll switch to in time.
Here's the matching step connected to u-bolts:
I've wrapped the coax ends in self-annealing tape to keep the water out and used some hook and loop wrap to keep a loop of coax in place.
It's resonant at 52.28MHz although the impedance is a little low. My rig can tune it up without any problem.
As soon as I called CQ on 52.525, Ron, VK2GO immediately responded - it's great that there's people around responding to random CQ calls. Thanks Ron.