The judgment considers in great detail whether single-sex handbasins for the washing of hands are required as well as single-sex toilets, and this appears to hinge on the difference in the applicable regulations (in this case the School Premises (General Requirements and Standards) (Scotland) Regulations 1967) between "sanitary accomodation" (which includes basins) and "sanitary appliances" (which doesn't).
This is something some posters and I disagreed about, whether (prior to Document T) floor to ceiling toilet cubicles but with mixed-sex common handbasins was permitted or not.
In Scottish schools the judge found that "The “accommodation” which must be segregated according to sex includes not only the flush toilets, but also the wash basins which must be situated near them under Regulation 15(3)."
The court also agreed that [51] girls have more and particular need of hand-washing over boys and that "Girls are therefore at a particular disadvantage having to use unisex toilet areas such as those in the main toilet areas. That is so even where there are individual cubicles with flushing toilets in them marked for girls only, because after relieving themselves they have to walk through a communal area where children may be waiting, with the particular hygiene issues relating to their hands already mentioned, and wash them at wash basins shared by boys" and so mixed-sex hand washing facilities were indirectly discriminatory against girls under the EA2010.
The first point really only applies to Scottish schools, but the second point is applicable everywhere the EA2010 applies, even if not a direct precedent in England and Wales.