| RefNo | Title | Date |
| EC/1896/02 | Clark, George Sydenham, Baron Sydenham of Combe: certificate of election to the Royal Society | |
| IM/Maull/000867 | Clarke, George Sydenham, Baron Sydenham of Combe | nd |
| IM/000869 | Clarke, George Sydenham, Baron Sydenham of Combe | nd |
| NLB/14/176 | Copy letter from an unknown correspondent, to Lieutenant Colonel Sir George Sydenham Clarke, Fellow of the Royal Society, 24 Cheniston Gardens, Kensington, W. | [18 January 1897] |
| NLB/15/573 | Copy letter from Robert William Frederick Harrison, to Lieutenant Colonel Sir George Sydenham Clarke, Fellow of the Royal Society | 29 October 1897 |
| NLB/28/727 | Copy letter from Robert William Frederick Harrison, to Messrs Harrison & Sons | 7 May 1904 |
| NLB/33/74 | Copy letter from Robert William Frederick Harrison, to Lieutenant Colonel Sir George Sydenham Clarke, Fellow of the Royal Society | 26 June 1906 |
| NLB/33/527 | Copy letter from Robert William Frederick Harrison, to Sir George Sydenham Clarke, Fellow of the Royal Society, 101 Onslow Square, S.W. | 24 September 1906 |
| NLB/48/780 | Copy letter from Robert William Frederick Harrison, to The Right Honourable Lord Sydenham [George Sydenham Clarke], Fellow of the Royal Society | 13 October 1913 |
| NLB/48/764 | Copy letter from John Rose Bradford, to The Right Honorable Lord Sydenham [George Sydenham Clarke], Fellow of the Royal Society | 9 October 1913 |
| RR/8/172 | Referee's report by James Thomson, on a paper 'On the determination of the rate of vibration of tuning-forks' by Herbert McLeod and George Sydenham Clarke | 5 November 1879 |
| RR/8/171 | Referee's report by Henry Charles Fleeming Jenkin, on a paper 'On the determination of the rate of vibration of tuning-forks' by Herbert McLeod and George Sydenham Clarke | 10 Jue 1879 |
| IM/Maull/000868 | Clarke, George Sydenham, Baron Sydenham of Combe | nd |