Hi
The oldest photo taken by J Brown in Rhyl was probably taken between 1874 and 1889. Local trade directories have three photographers called Brown:
Mrs Isabella Brown 7 Brighton Rd., Rhyl 1889
John Brown 3 Kinmel St., Rhyl 1874, 1876, 1883, 1886, 1889
Thomas Brown 3 Kinmel St., Rhyl 1868
Hope this helps.
Regards
Julie