What are the two foundations of a claim for sexual assault against the complainant?

The second foundation is the appellant's statement to the mother when confronted with the complainant's description of the bathtub incident. He replied that he was engaged in a period of self-gratification in the bathroom when the complainant walked in on him. He said he thought the door was locked. The complainant, however, was never asked whether she walked into the bathroom on the appellant and caught him in such a compromising position. In my view the failure to question the complainant about whether she ever walked in the bathroom on the appellant breaches the well-known rule in Browne v. Dunn.