When the 'Volumes 1-3' album of Bob Dylan's 'Bootleg Series' was first released in 1991, not even the most optimistic of fans could have foreseen that 17 years later the Dylan vault would not only still have some treasures left to offer, but that the standard of each album would remain so high with every subsequent plundering.

Lauded by critics and revered by fans, the 'Bootleg Series' has always been more than just a useful vehicle for filling in the gaps of the Dylan canon. Illuminating outtakes; blistering live performances and unreleased gems, the series has gone on to add an extra layer of depth to what was already an astonishingly prolific career.

If the first instalment, 58 rare and unreleased tracks spanning an entire career, whet fans' appetites it was 'Volumes 4-6' and the pivotal performances they contained, where the series really came into its own. Offering fans an insight into times they could only have read about, each edition came with a superior sonic quality, a thoughtfully produced 64-page booklet and an essay on the years at hand.

Listeners were treated to the infamous 'Judas' cat-calls, the raucous 1975 Rolling Thunder Revue Tour or, the pick of the bunch in this reviewer's humble opinion, a 1964 performance in Carnegie Hall, with Dylan on top of his game, clearly disillusioned with folk material and itching to go electric.

Let me say from the outset: the good news for any fans of the series is that 'Tell Tale Signs' does not fail to live up to the lofty heights of any of its predecessors.

In his autobiography 'Chronicles', Dylan described how, at his musical lowest ebb in 1989, he happened upon a jazz bar in San Francisco and emerged re-energised, with his muse rediscovered. Dylan returned to his roots, that is the roots of American blues music, and over the past two decades has gone on to what is universally acknowledged as the most fruitful stage of his career since the early 1960s.

Spanning from 1989 to 2006, 'Tell Tale Signs' covers this period and is packed from start to end with what can only be described as abandoned treasures. Alternative takes, unreleased songs, live performances and movie tracks, this edition of 'The Bootleg Series' is musically and thematically closest to his three latest albums, the acclaimed 'Time out of Mind', 'Love and Theft' and 'Modern Times'.

Much like many of the undisclosed songs on previous bootleg series releases, what is often most perplexing is how they failed to make it to the final cut when it came to his albums.

'Mississippi' is a case in point. On 'Tell Tale Signs' we get two treatments of the song which was recorded for the 'Time out Of Mind' sessions and eventually wound up on 'Love and Theft'. Stripped of all instruments apart from a smattering of electric guitar, the version on the first CD is a soulful, thoughtful song, with sorrow dripping from each word. A real find.

'Most of the Time' is transformed into a completely different song. Dylan's guitar and harmonica harking back to his civil rights days, the vocals more powerful and focused, the song emerges as an intense statement of lovesick regret containing much more impact than its 'Oh Mercy' predecessor.

The two versions of 'Dignity', originally recorded for the 'Oh Mercy' sessions but never included on the album, are compelling, if only to give listeners a glimpse at how a song simply never remains the same with Dylan. The first version is a rough two minute demo, forcefully sung with Dylan banging on the piano. Number two, however, couldn't be more different, part reggae, part jazz and with full band in tow, it is a stunning version, made all the more interesting by the inclusion of its earlier rendering.

Many of the previously unreleased tracks draw very heavily on his blues influences. No surprise then that the covers and reinterpretation of old blues standards like '32-20 Blues', 'Cocaine Blues' and 'Miss the Mississippi' are some of the strongest on the album.

For fans of Dylan, especially those who marvel at his creative processes at work, 'Tell Tale Signs' is simply a must have. However, it is much more than that. For anyone looking to find out about this older, wiser Dylan it is a highly recommended starting off point in discovering what will be looked at in years to come as one of the greatest Indian summers of any artist.

Padraic Geoghegan