It'll be as a 3Q code for a few reasons, the main one being that its ROG operated instead of the usual GBRf, but maybe also the fact that it is during the daytime helps with pathing allowances. With it being 3Q instead of 5Q, it gets put with the same priority as working passenger services (and I think high-speed ones), so it will be routed ahead of any other ECS and Freight moves, so they avoid most the congestion of daytime ECML. This could mean that they get a relatively constant speed for testing instead of it being quite stop-start, this is just a speculation though.