Yup, I concur. Even back in the day when I first went over -- when getting a spouse visa was easy and free and there were no shortage lists -- I was never able to get a librarian job, in spite of an MSLS and several years experience in academic libraries. I worked in a book shop for a while and years later managed to get a part-time library assistant post -- and that was only because I knew the library director!! Aside from the scarcity of jobs there tends to be an attitude that the American degree is not quite up to the British level. Or that was my experience.
You might want to explore a further degree in the UK. One thing I was contemplating for a while was doing an M. Phil. in Librarianship. This was a research degree so somewhat above an MLS, I believe. Four universities now offer it. The other thing I thought about was doing the Bibliography and Textual Criticism course at Univ. of Leeds but I don't think they offer that any more. Or, if you have any interest in the craft side of it, there are tons of places in the UK that offer courses in practical bookbinding. I know someone who went to West Dean College, which is highly rated.