Papers not originally part of the Palmerston personal archive have become incorporated into the semi-official papers that were catalogued by the Royal Commission on Historical Manuscripts (HMC). There are letters from Lady Palmerston's papers, including correspondence with Princess Lieven complementary to that in the British Library (Add MSS 45555-45556) and correspondence of Palmerston's brother Sir William Temple. Letters from Palmerston to Andrew Doyle and Sir John Easthope of the Morning Chronicle, which are mainly originals, were retuirned to Broadlands at some later date.
Correspondence to Lord John Russell from William IV, Palmerston, Sir Herbert Taylor and others was purchased by Wilfrid Ashley through Messrs Sotherans in 1917. Ashley also acquired Russell-Melbourne correspondence from the same source. Correspondence to Lord Melbourne now in the Palmerston Archive might have been passed by Melbourne to Palmerston; other correspondence, might have strayed from the Melbourne Papers.
In 1978 the Broadlands Archive Trustees were able to purchase and restore to the Palmerston Archive thirty contemporary copies of letters from Lord Palmerston to Lord Granville, British ambassador in Paris, 1831. The letters, which had been used in Bulwer's Life of Palmerston published in 1870, had presumably gone astray on their way back from the printer.