After studying this family I wondered why he would have died in Leicestershire when family seemed to remain in Mansfield? (Plus there are 2 deaths in 2014 Leicestershire - one bc.1929 and one bc.1934 - both of which are too young!)
Ronald's wife Amy Yates is said to have been born 22/8/1927 and died May 1991 Mansfield (tree on Ancestry).
Don't believe that Ronald himself is shown on 1939 - and probably a redacted entry. Index shows an entry for his father Albert E., plus some of his known siblings - no Lily shown with the family but she was possibly the one shown as a 'patient' elsewhere.
I agree that his parents were Albert Edward Lee and Lily Marriott who married 1919 Mansfield.
Albert died Mar.qtr.1942 Mansfield. At this point, not sure when Lily died.
Ronald Lee's birth entry was in Mar.qtr.1925 so could be a late 1924 birth or early 1925. Think that he's the Ronald Lee b.28/12/1924, who died July 2004 Mansfield (and not in 2014).
To proceed with certainty I think you need to get the birth certificate of Robert Lee Mar.qtr.1925 Mansfield, mmn Marriott, to confirm his birthdate and thus identify the correct death entry.
Annette