Graffiti?

Early walk this morning with J and L, the intention was to get out before the anticipated crowds, Easter weekend, school holidays, slightly relaxed Covid rules and crucially sunshine. The sun worked against us for the first part of the walk, warming but still low in the sky blinding us to our surroundings.
I am sure we have walked past this strange low brick shed many times but never noticed, or ignored, what is either a deliberate mural or some accomplished graffiti, either way intriguing. The extra adds a little context.