Good evening,
It could also be the 8th hussars, they also wore crossbelts. We would need to see the face of the sabretache to know for sure as that would show the regtl no and cypher.
I'm not sure about the 18th crossbelts but I have a copy of the "Light Dragoons" by Allan Mallinson. It is a history of the 13th, 15th, 18th and 19th Hussars by a former commanding officer of the 13th/18th Hussars. I will look it up just to make sure.
John915