Thank you for all your kind comments. The past five years have certainly been testing and at times exhausting, but for me and for what I was trying to achieve, they have been worth it. When it hasn't been blowing half a gale, I've even managed to get a glimpse of what it was all for!
I didn't judge the lee helm simply from going to windward: I am well aware that wth bilgeboards being part of the equation there is a lot that could affect this point of sailing. However, the lee helm was also apparent and thus indisputable, with the wind free.
I can't really relax and forget about it, because I live at anchor: I don't like the idea that I can't sail the anchor out as long as the boat sheers to leeward rather than helping me by tacking it out. Since I sailed down the harbour, we have had constant, fresh winds and it's been impossible to do anything to the sail. It's also been impossible really to relax :-{ However, although it is still too breezy to raise the sail and work on it, we are promised light winds and I am hoping for a calm period of a couple of hours or so to make my first adjustments.
I plan to move the sling forward about 100 mm, put a standing yard parrel from the yard down to the second batten down, add an extra batten to the luff hauling parrel and replace the tack parrel with a standing one from boom to the batten above it. I hope to bring the luff back about 300mm by these methods. I don't have many extra blocks and at this stage am disinclined to drill more holes in my boat for blocks and cleats for a THP anyway, untill I see whether the above modifications improve things. I have already altered the lead for the LHP. There was a brief period of calm yesterday morning, which enabled me to haul the sail up and try out the LHP as presently set up. It hauls that part of the sail well aft - too much so if anything resulting in a concave luff. However, the wind filled in before I could try anything else. We have had lots of days with barely a breeze this summer (when I wouldn't have minded one to cool me down!): typical that we should now have 5 days in a row where the wind barely drops below a fresh F4!
I have lots of nice little pottering jobs I want to do on deck, in light breezes and warm sunshine and am feeling a bit frustrated, to say the least. Ah well, no doubt the enforced idleness has done me good: I can't even do much in the way of writing emails, with the very poor Interent signal here. I've lost this page several times while typing this! On the other hand, I have a lovely view and am floating in water that is almost a Bahamian blue when the sun comes out: it's a lot better than being in an industrail area and inconceivaby better than being in a shed in an industrial area!!
By the way, a thousand thanks to my friends who have gone to the trouble of posting photos and video on this thread. I gather the videos are a lot of fun: I have yet to manage to download one!