Thanks, David, for posting this proposal on G2G. I am having a little trouble thinking of profiles where I would use a sticker for "born in Great Britain". I tend to only use "born in" stickers where I am reasonably confident of the birthplace – and then I use the "born in England", "born in Scotland" etc. stickers. If their birthplace is uncertain, I don't use a "born in" sticker.
The "born in the United Kingdom" sticker is not widely used and to a large degree its use was superseded by the more specific born in England/Scotland/Wales/Ireland stickers. Of the profiles that use it, a lot of them have certain birthplaces and many also have a "born in England" etc. sticker.
I think we also need to be careful not to confuse birthplace and nationality. I personally wouldn't describe a person who is a British subject because they were born at sea on a British ship, or born abroad to British parents, as "born in Great Britain".
Lastly, just one detail ... the Acts of Union which created Great Britain came into effect in 1707 rather than 1606.
Ian, co-leader, England Project