In the census of England and Wales for 1911 residing at 4 Rosslyn House, Rushcroft Rd., London SW is one Stephen Handel Lancaster, aged 33 and his wife Elizabeth aged 30. The couple are married and have no children. Mr Lancaster describes himself as an 'Orchestral Conductor working in Music Halls' and claims to have been born in Morecambe, Lancashire. Elizabeth's place of birth is Northumberland, Newcastle on Tyne.
Meanwhile in the same census of 1911, living at 70 Belmont Street, Southport is a William Rimmer, aged 49 with his wife Mary, aged 50 with their three daughters Emily, Marion, and Evelyn aged respectively 23, 21 and 12. William is a musical conductor, and Emily a music teacher. William was born in Southport, Lancashire as were his three children and his wife hailed from Chester.
Try as I might I have been unable to track down Handel Lancaster in any of the other census years, neither have I found a birth registered for him in and around 1878, nor a marriage for a Handel Lancaster and an Elizabeth.
If nothing else I think it can safely be said that Handel Lancaster and William Rimmer are not the same person.