Yes, a Great Britain essay. These are more often seen in various colors with corner check letters included. I'm not going to include a dealer site; search images for "Great Britain Queen Victoria essay" and you'll get a couple of examples. One seller says it is an 1879 essay by McCorquodale, made to bid to get the stamp printing contract. Perkins, Bacon & Co's contract had expired about then but got it back, and also produced essays for the new contract.
From my point of ignorance - Gibbons (not the current edition) shows the Perkins, Bacon essays for the 1879 1d tender, one of which appears identical to this, but with corner check letters. It says that they are known in deep brown.
Thank you hy-brasil and GeoffHa, I've found an image of this essay in Robson Lowe, page 185 second edition. Its a perforated strip of 6 with the check letters. He doesn't offer any information on colours.
Yes, it is Perkins Bacon surface printed essay for the 1879 tender to replace the 1d red, one of six designs submitted (page 226 of the S.G. Queen Victoria Specialist Catalogue). Unfortunately they had no experience printing surface printed stamps and lost the tender to De La Rue.
The ones without a W were printed from a plate of 120 in many different colours.
There were also reprints on thick card in four colours around 1913/14.