The motorcycle appears to be a bit later than 1900, and I would think it to be at least a 1910 model, and the photo could have been taken later than that (as would be suggested by their clothing?)
The bike has a "JAP" (J A Prestwich) V twin engine, but many motorcycle manufacturers of that era used JAP engines, so it doesn't identify the make of motorcycle, but may narrow it down a little?
"AW" was a Shropshire (Shrewsbury) registration mark.
And for anyone that may have difficulty finding that photo, here is the link: http://inky.me.uk/motobike_aw913.jpg