Thank you all for your lovely comments on my last post and here is my review of the 'light sabre' crochet hook.
Just for fun, I did try some stitching with the navy yarn in the dark and yes it is entirely possible to do it, why? remains the bigger issue! If you were trying not to disturb your partner in bed while they were trying to get to sleep or at the cinema I can only imagine the flashing movements with a small super bright LED torch might still be very annoying.
The real value of this hook, in my opinion, is with dark yarns or when sitting cosily in the evening without the need for a spotlight or increasing the general lighting when working with mid to darker yarns. It would possibly be nice to be able to purchase multiple hooks if they were interchangeable with the handle but that might lead to them feeling loose rather than the robust single unit. I don't have an idea how long the batteries will last as I'm hoping that will be some way off yet.
I bought mine in a 4mm size, as that is probably the one I use most, from Wool Warehouse and they are available from 2.5-6.5mm. There is a little video on the page and apparently, they have been featured in Simply Crochet but it doesn't say which issue. Mine cost £5.99 which I thought reasonable enough to try though when I think about it, all my aluminium and bamboo hooks together probably cost about £6 in total from ebay. However, when I 'saw the light', I had to have it!
In summary - a gadget which works, makes dark crochet much easier, the cost is reasonable if you are only purchasing one or two. I am really pleased with the quality and what this tool adds to my crochet.
I'd love to hear if anyone else has used this or if I've not answered a burning question just let me know.