Mach Two - I was working on the project at the time....
...apparently, with the Germans narked at workshare (the FCS, engines, radar, and airframe all by now being British-led) they took on the radome. They hadn't quite appreciated how difficult it was to make an RF-transparent pointy thing that's still strong enough to be thrown about the sky at high speed. When we finally got the results of radar/radome integration, it all went pear-shaped. Refraction's a sod...
They admitted fault (by not meeting the originally-agreed and carefully-written requirement specification) and we provided a solution... there wasn't much of an argument from the radome manufacturer, apparently one of the visual demonstrations of the effect was rather graphic.