Treating someone less favourably because of an assumption related to their sex etc can amount to direct discrimination.
Coleman v Skyrail Oceanic
 IRLR 398, Court of Appeal
A couple employed by rival travel firms got engaged. The firms were concerned about leaks and spoke to each other. As the man was assumed to be the breadwinner, it was decided the woman would be dismissed by her travel firm. Accordingly she was dismissed two days after the marriage.
The majority of the Court of Appeal upheld the employment tribunal’s decision that this was sex discrimination. An assumption that men are more likely than women to be the primary supporters of their spouses and children is an assumption based on sex. Therefore, the dismissal of a woman based on an assumption that husbands are breadwinners and wives are not can amount to discrimination under the SDA.
Horsey v Dyfed County Council
 IRLR 395, Emloyment Appeal Tribunal
A female trainee social worker wanted to attend a two-year social service course in Maidstone. Her husband had been appointed to a permanent post as librarian at the House of Commons. The Council refused to send her on the Maidstone course as she had agreed to return to work for the Council for at least two years following her course and the Council thought that in the light of her husband’s appointment she would probably not return to serve her two years with the Council afterwards.
The EAT held that there was direct discrimination. The words “on the ground of” sex etc include cases where the reason for the discrimination was a generalised assumption that people of a particular sex etc possess or lack certain characteristics. The Council would have treated a married man differently, as it assumed that the wife would follow the husband’s job rather than vice versa. There was therefore (direct) sex discrimination.
Noble v David Gold
 IRLR 252, Court of Appeal
In the employer’s warehouse it was the women’s job to unpack, sort, arrange, price, label and repack books coming into the warehouse from publishers. Men also worked in the warehouse but doing the heavier tasks of unloading, carrying and lifting. The employer was making serious losses due to a fall off in work. Since it was the lighter side of the work (done by the women) which had diminished, it dismissed some of the women on grounds of redundancy.
The Court of Appeal held that the lower tribunal was entitled to find there was no sex discrimination. Lord Denning seems to have based his judgment on “the natural division which comes about because of the different physical qualities of the two sexes”. However, the Court of Appeal judgment most in line with the two later cases above (Coleman and Horsey) and the House of Lords decision in Roma rights is that of Lord Justice Lawton, unsuprisingly as he subsequently gave the leading judgment in Coleman. He commented:
“The [SDA] provided, subject to a few exceptions, that employers when offering jobs must not assume that women are less capable of doing them than men, and vice versa. This does not mean, however, that a particular applicant for a job, whether male or female, can do it. Much will depend upon the applicant’s personal attributes. If the job is one which requires the lifting of heavy loads, a woman of slight build may not be capable of doing that kind of work but one with the physique of an international discus thrower may be. Whether a woman applicant for a job can physically do it must be a matter of judgment for the employer, and he should base his judgment on his own assessment of the candidate, based upon her physique and his experience of what other women doing that kind of job have been able to do. What he must not do is assume that all women are incapable of doing a particular job.”
Lord Justice Lawton considered that the issue going to the root of the case was whether the employers made the allocation of work on the assumption that no woman was capable of doing the heavier work. He considered that the employers had not made this assumption: “their experience had been that their female employees, including the three applicants in this case, had turned out to be incapable of doing the heavy lifting work.” For example, a director had said in evidence that they would take on a woman who could do heavy duty lifting if one came along. The industrial tribunal were entitled to come to the conclusion that “there was a division of work, that it was not based on sex but on practical experience of organising the work in the warehouse.”