Cecil Sharp collected several tunes from Locke around 1909 - see http://www.btinternet.com/~radical/thefolkmag/jlocke.htm
David Sutcliffe has an entry on his website Sharps People
A cylinder recording of Locke playing an unnamed hornpipe is held by the British Library Sound Archive. This can be heard at http://sounds.bl.uk/View.aspx?item=025M-C0037X1590XX-0100V0.xml (where it follows an unnamed singer singing "There is an ale house [Died for Love]"); or on its own at http://eds.efdss.org/back_copies/EDS_Winter2006.html
This tune is often referred to as "John Locke’s Polka" but in the Musical Traditions article "Name that tune" Philip Heath-Coleman argues strongly that the tune as played by Locke was clearly a hornpipe - also that it is a version of the Bristol Hornpipe.