- 4th July 2009, 1 at Fairlop Waters
- 12th May 2009, 2 at Fairlop Waters
- 25th-29th April 2009, 1 at Fairlop Waters
- 22nd April 2007, 1 at Hainault Forest
- 24th April 2005, 1 at Fairlop Waters
- Grasshopper Warblers are reported as being a former or occasoinal breeding bird in Hainault Forest pre 2003 by the late Mr. Mike Dennis
- In the 1997 edition of Dominic Mitchells 'where to watch birds in the London area' it states that they have been heard 'reeling' in spring and early summer, but that they did not breed.