Seamer's surviving drawings are private records of family and friends and exercises in composition and texture, informed by his upbringing as a calligrapher and his devotion to seventeenth-century art. It is easy to discern in the elegant curls of the child's hair in cat. 21 the ancestry of Seamer's drawing style. In 1675 he was apprenticed to the goldsmith-banker Sir John Johnson and only a year later published the first of two books on calligraphy; the second in 1684. In 1719 Seamer's 'early Genius, not only to that most polite, commendable, and commodious Art of Writing, but those of Drawing and Engraving' were praised. Yet Seamer's achievements were short-lived. By 1764 the author of a biographical dictionary of penmen 'can give my reader very little intelligence concerning this James Seamer. I cannot so much tell when or where he lived.'
Seamer was best known as an art collector. He assembled one of the great collections of prints and drawings of his day which was 'well known to the Curious; and from his Application for about 50 Years in the collecting, its believed it will be the best that has been sold since the late Lord Somers's." No catalogue survives but advertising for its sale in 1737 pointed to Seamer's ‘several excellent Limnings and enamell'd Pictures of Pettitoe, Cowper, Hoskins, &c. Also his well-known Curious Collection of upwards of 8000 Prints and Drawings of Raphael, Julio Romano, Mark Antonio, Anibal Carracci, and all others of the best Masters of the Italian, German, Dutch and French Schools. Amongst which are near a Thousand of Vandycke's Heads, mostly by the best Engravers.' Seamer owned an oval self-portrait by Isaac Oliver, which was probably the one subsequently owned by Horace Walpole. At Seamer's death, Vertue recorded that 'his great Age gave him an early opportunity and acquaintance with Artists long ago dead, as Mr.Faithorne, Sr.P.Lelly, Mr.Simons Modeller, Quellin. Sr.Chris Wren &c.’ In 1678 Seamer had met the enamel painter Jean Petitot, who had originally come to England in 1637 with letters of introduction to Theodore de Mayerne.
Vertue also knew of Seamer's copies after Samuel Cooper's work in crayon and noted: 'Some sketches of heads with the pen Loosely done good Expression done by Coll. Seymour Banker. in the manner of Inigo Jones. multitudes he has done so.' One hundred and fifty-five of these were acquired by the silversmith and art dealer Panton Buteux (1722-99), and offered at his sale on 12 June 1799. Examples of Seamer's drawings are in several collections but have been quite widely mis-attributed due to the similarity of Seamer's drawings to better-known artists. For example, a small group at the Ashmolean museum was previously attributed to Isaac Oliver. At the Courtauld Gallery is a head in profile that is part calligraphy, which at one time attributed to Jonathan Richardson the elder but which is surely the work of Seamer. At the British Museum are two pen and ink drawings attributed to Lely (and previously to Richardson) which are characteristically Jonesian sketches of Seamer.
- James Seamer, Arts masterpiece or The pens glory a copy book, London, 1676 and James Seamer, A compendium of all the usuall hands written in England, London, 1684. See also Walter Shaw Sparrow, 'Colonel James Seymour or Seamer: Goldsmith, Banker, Penman, Engraver and Collector', Country Life, vol 86 no.2221, 12 August 1939, pp.142-3.
- Edward Hatton, Merchant's Magazine, London, 7th ed 1719.
- W. Massey, The origin and progress of letters, an essay, London, 1764, p.127.
- London Daily Post, 11 December 1736.
- London Evening Post, 22 January 1737. His jewels and plate were auctioned on 14 September 1736 and two freeholds in Salisbury Court, Fleet Street, were sold in February 1738. Creditors eventually received 7s in the pound. London Evening Post, 2 September 1736; London Daily Post, 10 February 1738; Shaw Sparrow, 'Colonel James Seymour or Seamer: Goldsmith, Banker, Penman, Engraver and Collector', Country Life, vol 86 no.2221, 12 August 1939, p.142.
- Vertue, vol. II, p.47.
- Vertue, vol. III, p.86, vol. IV, p.83.
- Vertue, vol. II, p.47; vol. V, p.50.
- A catalogue of the valuable drawings and prints, some pictures, models by Rysbrack… late the property of Mr. Panton Betew, London, 1799, lots 3-6 & 165.
- David Blayney Brown, Early English drawings from the Ashmolean Museum, Oxford, 1982, pp.117-9, nos.208-11.
- Courtauld Gallery, museum no.D.1952.RW.1604.
- British Museum, museum no.1954,0604.1 and museum no.1954,0604.2.