Dad: this is one of Pooch's expressions that we have been trying to capture for some time. Here you can see the 'grin for passers-by'...
the shadow in the foreground is of two people about to pass us, and Pooch is ready and waiting with his "aren't I cute, how can you resist saying hello to me" face.
Mostly it's very effective, with the result that few people who encounter this face fail to stop and give him a pat. :-)
Like most westies, Pooch loves making new friends!