Upstream from the lock, the main weir connects the second island to the opposite bank on the Kennington, Oxfordshire side.

In the reign of Edward III there is an account of the immemorial conflict between millers and bargemen when "the men of Oxon broke down the locks of Sandford".

The lock was passed on to the Thames Navigation Commission in 1790 and lengthened in 1795, under the direction of Daniel Harris, the Oxford gaoler, at a cost of nearly £1,800.

Weirs, like the one at Sandford Lasher, generate powerful currents that can trap and hold a victim (and often attempted rescuers) underwater at the base of the structure; hence their reputation as "drowning machines".

[3] John Richardson Currer, brother of Charles Savile Roundell and student of Balliol College, Oxford drowned in February 1840 while attempting to row a skiff through the lasher pool.

[4] A 16-year-old pupil of the Cowley Diocesan School, Edward John Templar, the son of the Vicar of Great Coxwell, drowned on 21 May 1864 after diving into the water and saving the life of another boy, a non-swimmer who had accidentally fallen into the weirpool.

[7] At the weir, a 19th-century obelisk records the deaths of five Christ Church students who drowned here - Richard Phillimore and William Gaisford in 1843; George Dasent in 1872 and Michael Llewelyn Davies and Rupert Buxton in 1921.

[10] Michael Llewelyn Davies was the foster son of writer J. M. Barrie, and one of the main inspirations for the character of Peter Pan.

The Thames Path follows the western bank to Iffley Lock crossing the Hinksey Stream on the Kennington Towpath bridge.

It is also mentioned in The Dictionary of the Thames by Charles Dickens, Jr.[15] It is notorious to all rowing men and habitue's of the river that Sandford Lasher has almost yearly demanded its tale of victims and it is almost inconceivable that people will continue year after year to tempt fate in this and other equally dangerous places In Tom Brown at Oxford, by Thomas Hughes, first published in 1861, the eponymous, principal character has a narrow escape after accidentally rowing a skiff over the weir and into the lasher.