To allow the RAF to write the operating manual and work out the best way to use it and also the limitations on it in service.
Why was that not being done at the same time the plane was being built? I've worked on commissioning large industrial plant and we had to have the SOPs, operations manuals, and all the staff trained ready for the day after the various contractors walked out. There then followed a one month period to confirm that our manuals matched the practical implementations of the equipment. (It was our first completely computer controlled thin film plant c/w all sorts of new and novel control gear that had never been used before). Oh and from day one of the confirmation period we were producing product for shipping, we just had a 100% scrappage allowance for a month.
If you've still to work out the best way to use it and what it's limitations are then it sounds like you're still at the specification stage of the project.