Sorry for the delay replying - I'd definitely like this if it's still available. The smartphone thing sort of works but you have to get everything set up, then start the app timing AND trigger the shutter within two seconds. And it really only works well in a dark room with a smallish light source such as a torch. It's a bit too fiddly to be worth while for everyday use.
I'll send you an email with my details - paying by PayPal would be best for me, or I can send a cheque. Let me know how much it will be.
Thanks for the advice on smartphones. Have emailed you about sending it, including smart phone adaptor, as no-one else jumped before you.
Vasily Florin, the meter builder, suggests using one of these single LED lights for your keyring with the smartphone adaptor. Says multi leds can be misread, possibly because they are not synchronised, and the sensor may be more accurate with single pulses.
Paypal would be fine, I'll send cost when posted.