http://www.survivinglogic.ca

Lead by Alejandro Guijarro gathers X-Ray and Ultra-Violet renditions of old master paintings at the Tristam Hoare Gallery.

See more at:

https://www.theguardian.com/artanddesign/gallery/2017/feb/28/masterpieces-hiding-in-old-master-paintings-in-pictures-alejandro-guijarro

and

http://tristanhoaregallery.co.uk/exhibitions/lead/

Worth a visit – 6 Fitzroy Square