A very similar model of newel post finial appears on the staircase at Hatfield House, Hertfordshire. See H.A Tipping, English Homes, Period III, Volume II, London 1927, pg 333 - 335, particularly figure 422.
Another similar lion finial formed part of a group of four heraldic newel post finials at Bradninch Manor, Devon, but now removed. See H.A Tipping, English Homes, Period III, Vol II, London 1927, pg 121 - 126, fig 125 for the Dragon of this group.
See also Helena Hayward (Editor), World Furniture, London 1965, page 59, fig 183 for a table at Lambeth Palace with similar lion supporters and a court-cupboard with very similar twin supporters sold at Christie's South Kensington, 3 November 1999, Lot 606.