Hi BW. Thank you for your reply. You have actually made me look at the photo quite diferently ( my son took the photo - I did not actually see the insect ). After looking at pictures of the caddis fly I realised that the bulbous body is no such thing, but is actuall the wings of the creature but the photo is lacking in definition. Also the "antennae" is actually two normal antennae but they overlap each other for the first three quarters of their length. So after looking at it differently I now think it may be somekind of Lacewing. But it's luminescence ( as described by my son ) is strange.
I'm very grateful for your help.
Good team work - lacewings produce a wax that coats them and they look white - apparently!
Finally, I can't vouch for the accuracy of this info, but it is fascinating and would provide an explanation of the white appearance