In Rolawn v. Turfmech,  EWHC 989, infringement of UK registered and unregistered designs in a wide area mowing machine was alleged. The judge found that the defendant (despite their assertions to the contrary) had taken a close interest in the claimant's machine in developing their own.
The main issue was therefore whether they had come too close as a result. The judge found that the individual similarities, and the totality of them, were at the idea or textual level, whereas designs protect not an abstract idea or concept, but a physical manifestation of it. There was thus no infringement. So far as UK unregistered design right went, to catch the defendant the claimant's design had to be stretched to the point of invalidity as an excluded "method or principle of construction". The case is of interest in showing that, these days, the UK Courts no longer regard copying as per se damning - the question of similarity will ultimately always be relevant.