Roy Precious - Antiques & Fine Art has dated this piece to the 1800s.
They were married on the 1st of May 1810 in St. George's, Hanover Square, London. Their union produced nine children.

Elizabeth was born on the 1st of October 1787 in Montrose, Scotland. Her father, Thomas, was the Town Clerk of Montrose and her mother, Elizabeth Guise had been born in Gibraltar in 1755.
Henry Westmacott was born on the 13th of October 1784 in Hanover Square, London. The Westmacott family were leading sculptors of funerary monuments in the 18th and 19th centuries and also specialised in carved chimney pieces and other forms of architectural sculpture.

Henry produced work at a young age, carving a marble monument to Henry Roberts at Swanscombe, Kent in 1796 when he was 12.
Thereafter he produced nearly 50 church monuments. Between 1806 and 1810 he did work in connection with John Flaxman's marble monument to Horatio, Admiral Viscount Nelson at St. Paul's Cathedral, London.

Henry died in 1861 aged 77.
The National Portrait Gallery has Thomas Phillip's sitter's book in which this portrait and that of her brother Captain Stewart are included (also on this website).
THOMAS PHILLIPS R.A. (1770-1845) was a leading English portrait painter. He painted many of the important and wealthy of the day including scientists, artists, writers, poets and explorers.

He was elected ARA 1804, RA in 1808, becoming Royal Academy Professor of Painting in 1825.
Phillips was a contemporary of Lawrence and offered a more subdued style based on his study of Old Masters. "His best works are full of character and show him to be in the top rank of portrait painters" (The Dictionary of Portrait Painters in Britain up to 1920.)
SIZE: 40.5 x 35.75 inches inc. frame
30 x 25 inches canvas size.
PROVENANCE: By family descent.
Deceased Estate, Dorset.
VERSO: Three handwritten labels including one tracing Elizabeth's descendants to the present day.
Roy Precious - Antiques & Fine Art has dated this piece to the 1800s.
Roy and nadine precious: specialists in portraiture from the 16th to the 20th century. Established in 1972.
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