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It's time for Radiohead fans to do a gentle sway in appreciation for an astoundingly beautiful song that somehow never saw the light of day before today. 'I Promise' is streaming for the first time, check it out on Gigwise below.

The song is an acoustic offering with goosebump-inducing strings dubbed over the top, Thom Yorke's emotional, tear-inducing vocal tone, and marching percussion. Taken, presumably, from the OK Computer era since it's included on the reissue named OKNOTOK, it harks back to a very special era in Radiohead's career.

The forthcoming digital only release, which is available to pre-order before it's out on 23 June, features the original album, eight b-sides, and three unreleased songs - 'Lift' and 'Man Of War' are the other two.

All tracks are remastered from the original master tapes and it's a release put out to commemorate 20 years since the landmark album that brought us amazing songs like 'Airbag', 'Subterranean Homesick Alien' and 'Karma Police'.

Hearing an album that already sounds so perfect, diverse, and exciting, slightly altered from the original is an enticing propitiation, but to tie you over until then 'I Promise' is perfect for whacking on repeat.

The release of 'I Promise' is accompanied by a poignant new video for the song, directed by Michal Marczak who previously directed the vignette for 'Identikit' from A Moon Shaped Pool, as well as the clip for Mark Pritchard’s 'Beautiful People' featuring Thom Yorke.

Elsewhere, after teasing fans with some mysterious clues such as a crop circle logo on the Glastonbury site, Radiohead were finally announced as headliners of the Pyramid Stage, which is bound to be one of the highlights of the summer.

More about: RadioheadGlastonbury Festival