Rothbart did many commissions for Queen Victoria. These could be part of that as she commissioned a set of Prince Albert’s childhood home, or they could have been commissioned by her brother in law. The theatre watercolor was for Queen Victoria. The others don’t say.
“Melusine” triptych. ca. 1910. Collection of the Worpswede Museen, In the public domain in the United States because it was published before January 1, 1924. via http://www.the-athenaeum.org/art/full.php?ID=94251