Silver Vesta Box

Have a silver vesta box Joseph Gloster 1904.
It has the usual flip top, but also the side pulls down to expose
a oval picture frame.
I have never seen another one like this, in very good condition
Some idea of worth please as i am selling on Ebay.
Ken Kenlin.l

I would estimate the value at £150. But all you need is for two collectors to both want the same item and then the price could easily go up to £350+.