Holtslag studied recorder at the Sweelinck Conservatorium in Amsterdam (now Conservatorium van Amsterdam), Frans Brüggen being his great inspiration, graduating with distinction in 1980. He has toured worldwide as a recorder and flauto traverso player, performing with musicians such as Gustav Leonhardt, William Christie and Roy Goodman, as well as with ensembles such as The English Concert, Orchestra of the 18th Century, Akademie für Alte Musik Berlin, La Fontegara Amsterdam and Trio Noname. He has recorded numerous CDs for major labels, including Hyperion, DGG/Archiv, Globe, Aeolus and Chandos.
In 2011, he recorded a CD on the Aeolus label entitled Awakening Princesses, using original 18th-century recorders from the Bate Collection of Musical Instruments of the University of Oxford as a documentary-research project.[1]
In 2016 a Bach CD was released (also on Aeolus), using an original transverse flute from Bach's times.[2]
