This is "A Man holding a Glove" by Jan Gossaert, painted in the Netherlandish tradition. We don't know who the sitter is, but his fashion suggests a date towards 1530. Notice how his doublet and gown are lined with fur - this probably indicates that the portrait was painted during the winter months. The pose of the sitter's hands resting on a table placed at an angle recurs in other undated portraits by Gossart.
The painting is rather small, and it shows just how quickly and skillfully Gossaert could work. He might have been under pressure to complete this portrait in a short amount of time. The use of wet-in-wet technique for the fur is particularly impressive, as well as the way the paint has been feathered into the eyes and cheek.
The panel is made from a single board of oak, which was cut in an unusual way - across the width of the tree rather than radially. Despite this, the painting is in good condition, and it's clear that Gossaert knew exactly what he was doing. You can still see unpainted wood and barbes on all four sides, where the ground and paint end. It's fascinating to think about how this portrait ended up in the collection of King Charles I - it must have been a prized possession for him.
A Man holding a Glove hangs in The National Gallery on Trafalgar Square, London — free to enter. Point your phone at any artwork there and audioguide.london plays a free audio guide in six languages — no app download needed.