From Law wiki, the wiki for law research

[1991] 2 AC 447 (HL). The defendant was tried and convicted of two Indictments of rape against his two daughters. The basis of his appeal was that the daughters had colluded in their evidence, and by allowing evidence from daughter to stand in the indictment against the other, the jury had been unduly prejudicted by the cumulative evidence. The defendant argued that the test laid down by the House of lords in DPPVBoardman1975, for cross-admissibility of multiple allegations, was that there should be a striking similarity between the offences alleged (as the term 'striking similarity' would be understood when considering the admissibility of evidence of disposition). In fact, in this case, the offences, although despicable if they were proved, were 'commonplace' rapes with no sriking features at all.

The House of lords held that, although 'striking similarity' was one of the criteria by which the cross-admissibility could be determined, it was not the only one. Whether the evidence had sufficient probative value to overcome the inevitable prejudice it would create against the defendant was to be determined on the facts of each case. In the present case, the large number of points of similarity between the offences, even though these similarities were not in themselves particular striking, was sufficient that their probative value was very high.

However, the other safeguard set out in Boardman was not disturbed -- it was still necessary that the judge rule out all possibility of collusion between the complainants before admitting the evidence. This safeguard was itself abolished in R v h (1995).