(d. 1786), architect, s. of David Henderson a mason and architect of Sauchie in Scotland.
c.1774 - 9 Rome (c.1774 - Sep. 1778), Naples (27 Sep. - 10 Nov.), Rome (Nov. 1778 - 26 May 1779), Venice (20 Jun.)
Henderson was destined to follow his father's architectural profession of his father David, and was sent to Italy to complete his education. It is usually stated, without much evidence, that John set out on his travels from Edinburgh around 1774, but his itinerary before reaching Rome is uncertain. Once he had arrived there, however, he was noticed by Thomas Jones in his Memoirs. Most of these incidents record Henderson in the company of his English counterpart Thomas Hardwick, as when the two of them ascended to the ball below the cross on St Peter's (13 Jan. 1778), or when, together with Robert Furze Brettingham, they observed Vesuvius in eruption (27 Sep. 1778).1 Thomas Hardwick's own travel journal corroborates some of these movements, although he returned almost immediately to Rome, whereas Henderson lingered on in Naples until 10 November 1778, according to Jones.2
During Henderson's absence from Rome, Soane and the Bishop of Derry had arrived there. The Bishop invited suggestions for a new summer dining room at Downhill, and Soane's novel submission was whispered to be 'a copy of another made by Mr. Henderson ... before my arrival'.3 Sometime between Henderson's return in November and Soane's departure for Naples as the Bishop's prot?g? on 22 December, Soane requested that the rumours of plagiarism be quelled by an 'objective' comparison of the two competing designs. A kind of architectural duel ensued in which the architects named as seconds their boon companions Hardwick and Brettingham, respectively. No shot was fired and the combatants retired in a state of grudging acceptance from which their friendly relations never really recovered. The fickle Bishop had already made up his mind in favour of Soane.
A half century later the urgency of the debate about the competing schemes had hardly diminished in Soane's mind, thanks in part to Brettingham, who recorded the duel's outcome. In a letter written to Soane he mentioned wishing 'to copy that Room you designed for L.d H.... I should like too to have Copies of the others of the Rome [sic for room]'.4 In 1832 Soane illustrated his own version of the dining room with apsidal ends alongside Henderson's plainer one, supposedly derived from the plan of the Pantheon.5 But in truth Henderson should have counted himself lucky to have avoided what Soane later ruefully called 'the magnificent promises and splendid delusions of the Lord Bishop of Derry'.6
According to Jones, Hardwick and Henderson left Rome together. They returned home by way of Venice.7 In 1793 Sir William Forbes exclaimed in the gallery of the Colonna Palace in Rome: 'Poor Henderson, the architect ..., in one of the plans which he drew for the Assembly Rooms at Edinburgh [begun in 1784], had borrowed this idea ... [of] a recess at each end, elevated in this manner and separated by a screen of columns, which would have produced, I doubt not, an excellent effect'.8
1. Jones Memoirs, 68, 79. 2. Hardwick jnl.MSS, ff.25v, 28r. 3. Soane, Memoirs, 15. 4. Bolton, Soane, 19 - 20 (22 Dec. 1778). 5. J. Soane, Designs for Public and Private Buildings, 2nd ed. [1832], 39 - 40. 6. Soane, Memoirs, 14 - 16. 7. Jones Memoirs, 89. ASV is 760. 8. Forbes jnl.MSS.
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