Your search for "upsetters/pressure sounds (uk)" revealed the following:

JUNIOR MURVIN [Cross Over / I'm In Love]

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ID No. 222404 Label BLACK ART (UK) Production Upsetter Late Genre Reggae70sLate / Male Vocal Condition EX- Track Police & Thieves Soundclip* 12ディスコミックス。

LEO GRAHAM [Pampas Judas]

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ID No. 231926 Label ETHNIC (UK) Production Upsetter Early Genre Reggae70sMid / Male Vocal Condition VG Soundclip* レオグラハム「Bad Lamp」と同オケでクラビの音冴えてます、プリンスジャズボのMC付き。 ジャマイカのアップセッターズ盤では「Doctor Demand」というタイトルです。