Um... Well I thought I did! ☺️
Your birth year looks pretty good, the Victoria Melbourne looks pretty good, the Hy Maxwell would refer to her father, Henry Maxwell Mathews, and the Potter to her husbands father, Robert Potter.
Your find here has different dates than those on the headstone.
John Potter d 1874 aged 54 and Sarah Annie Potter d 23 Feb 1875 aged .. I think it said 61, but I know it showed early quite early deaths for them both It also has names of children. So.. A bit of a puzzle. I've had this headstone in my mind for quite some time now, until I could find more info that might tell me whether they were mine or not! Now looks like the time!!
But those names you have just posted make more sense, as they have what appears to be both father's names! The headstone I have has chn's names, but I don't know about any chn the Potters may have had!
If I shift off typing this message to check the link to Findagrave now, I'll get booted off, lose this message, and have to log in again- for some reason this silly ipad is locking me out, when I try to go back to here for instance! Not just on here, but other passworded sites as well, and I'm not presently unable able to flick between 2 different sites. Just started doing that a couple of days ago, so I don't know why, or how to sort it! Maybe it will fix itself, I have no idea!
Anyway,I'll go and check my PC see if I can find it in there and get a link. Can't reduce the size of a photo on the iPad, and it's too big for here, so a link would be best. But I'm inclined to be favouring your find now Willsy! All grist for the mill huh? And I just let my dinner burn while I was doing this message!

I Shall return! You are a star!
Modified to add link to the gravestone
http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GSln=Potter&GSfn=John+&GSbyrel=all&GSdy=1874&GSdyrel=in&GScntry=15&GSob=c&GRid=133687575&df=p&John died aged 41 Sarah Aged 45
Thanks again
Jeanne 😄