Marble and Slate clock

This clock was given to my father in law when he roomed with an English couple while attending university. It never worked and moved all over with my husbands family. After my father in law passed away and my mother in law was downsizing, we inherited the clock. We have spent a fortune to get it refurbished and in working order.

The clock repair man offered us approximately $1500.00 and said it wasn't worth much more than that. We aren't interested in selling it but would love to know it's make and approximate age if someone could help.

Thanks!