Calder’s ex-wife gathered the collection from his time at the independent music label Immediate Records.
The label was short-lived as it was impacted by financial difficulties soon after it was established.
Hughes, a vinyl specialist from Bristol, said he “jumped” at the chance to look at the rare collection.
Calder – who died in 2018 – was credited with helping The Beatles score their first hit before he went on to work with Fleetwood Mac, PP Arnold and the Small Faces.