Thanks to all of your help I have been able to access the 1921 census and located Ellen , formerly Long, married to Ernest Purcell living at 74 St Joh's St in Liverpool - the same address as on her former husband's death notice in 1915, She had 3 sons at this time.
I am almost certain this is the same Ellen that I am looking for as she was also born in Waterford, Ireland but as her birth date is a few years later than my relative I am going to confirm by her marriage certificate giving her father's name.
As I haven't used these forums before thankyou to each of you that helped and excuse the errors I made!