Are they actually from London or did they just watch a f**ktonne of Mary Poppins and decided Dick Vandyke's god awful attempt at a cockney accent is the Baws and stole it?? I don't know much ork lore. I'm curious
Who da zogg iz Mary Poppins? Lissen, it donz madda where'z weeb git our accent. Da onlee fing dat maddaz iz crushin' dem uumies! Woss up, Boss Badrukk!
Orks have their own language, that has a series of different sounding grunts they mash together into words. When they run into a word they don't understand, they just take existing grunts and rearrange them as best they can to sound like that word. By coincidence their attempts sound like cockney. That's the lore explanation. The real explanation is...the guys at GW needed a way to make them seem brutal but not serious so they went with that.
I'd love to see drunk scottish Orkz. Sorta like Old Man Henderson, except not quite as a good perhaps. Because you can't get better than Old Man Henderson.
To be fair, killing a Lovecraft deity basically throws him way up above most beings. I honestly hope we can get a decently large number of Ork accents to choose from, it would be kind of boring if we all heard the same Ork.