The artist Walter Greaves , who began tuition with Whistler in 1863 .
Who knew Hiffernan well , said that she had a son called Harry but no trace of him can be found in official records .
The artist Walter Greaves , who began tuition with Whistler in 1863 , and who knew Hiffernan well , said that she had a son called Harry but no trace of him can be found in official records .