I have a William Robert Mumby in my files. DOB Feb 28, 1897. No specified place of birth.
His parents were Christopher Topper Mumby, born 1852 in Nettleton, Lincolnshire, England & Sarah ? spouse, born 1853 in Nettleton. (I also have another spouse, Johanna born in 1853 in Nettleton. Perhaps Christopher married twice). Other children born to Christopher and Sarah were Betsy Jane born Oct 15, 1876, Annie Maria born/bapt August 18, 1878, Elizabeth Margaret born January 1881, Edith Martha born March 4, 1883, Samuel Percy born Jul 18, 1886. All the above children born in Bigby, Lincs.
Christopher & Sarah's abode was Bigby Top Farm. (Might have a bearing on Christopher's middle name Topper).