Lady Greenwood was born Margery Spencer on 20 December 1886 in Sapiston, the daughter of Rev.

Walter Spencer of Fownhope Court, Herefordshire and Anne Elizabeth Hudson of Bache Hall.

[3] On 23 May 1911, she married Hamar Greenwood, a Canadian-British politician and lawyer who sat as a Member of Parliament for Sunderland, in a ceremony at St Margaret's, Westminster.

[3] The wedding festivities were attended by many political leaders including H. H. Asquith, Sir Harry Verney, 4th Baronet, Wilfrid Laurier, Joseph Ward, Annie Botha, David Lloyd George, John Burns, Herbert Samuel, 1st Viscount Samuel, Robert Reid, 1st Earl Loreburn, Lewis Harcourt, 1st Viscount Harcourt, Walter Runciman, 1st Viscount Runciman of Doxford, Donald Smith, 1st Baron Strathcona and Mount Royal, Sir Charles Rose, 1st Baronet, John Redmond, Leo Amery, and Wilfrid Ashley.

[3] She was extremely interested in politics, so much so that, during World War I, her husband claimed that she "knows every Member of the House of Commons, which she attends regularly".

[3] In 1948, she attended a dinner and reception alongside Princess Elizabeth for Eleanor Roosevelt, hosted by Pilgrims Society, at the Savoy Hotel.