Exclusive: Art historian points to ‘bad craftsmanship’ in 17th-century work entitled Samson and Delilah

Doubts about whether Peter Paul Rubens painted the Samson and Delilah picture in the National Gallery have been revived by new evidence.

Forty-five years after it was bought for a then record price, it is being dismissed as a 20th-century copy of a long-lost painting by the 17th-century Flemish master.