Well, it seems there is some problem with Urchin post, I cant find any diagram.
Anyway, what I see everytime is the spit pointing directly to the target and spraying like mad, never parallel. In your diagram, you should imagine the spit's nose tracking the 190 movements every time till the overshoot. And, if the overshoot is achieved due a break turn of the 190, instead scissoring, the resulting angle woulbe be of 90 degrees or more, so, the supposed flat turn of the spit will place it more than 400 yards away of 190 guns in the first wide circle just to end at the 190 tail in 5 seconds more.
You should also consider the corner speed of the spit, well, not the corner speed but the range of speeds where it outturns the 190 at any speed. You will probably find out that the spit, even above 300mph, can outturn a 190 at any speed.