Mrs McKecknie mentions G. Bonner in her book “British Silhouette Artists and their work: 1760-1860”. A museum in Norwich alerted her to a silhouette they possess signed by a G Bonner. It is a bust-length silhouette of a boy cut from black paper and highlighted in gold. The style of the boy’s clothes dates the silhouette to the 1840s. Unfortunately, no other information can be found about this artist.
Source: McKechnie (Author of, British Silhouette Artists and their Work 1760-1860)
Bonner, G. (McKechnie Section 1)