The 4 main criterias a judge will look on is Pay, location, hours of work and differences in the role, for pay and location, unless the employee is willing to move further away from home to work, then any longer commute would likely mean increased cost on travel and less time to spend at home, where possible, the employer should look to re-deploy current employees to other stores equidistant or closer to where they live, they should not be out of pocket on either pay or location.
Hours should both be the same as is in previous role and should not conflict with an employees availability (if it does then further probing would be made to ascertain why said employee is unavailable, if it's for a reason such as not wanting to work lates, then the judge won't look favourably on that.)
The last criteria is the one that Tesco is trying to hornshoe in as "soft structure changes" if the judge were to be presented with role packs of the previous role and new role. They would deem the additional responsibilities of a now redundant manager role being added to another managers role is not a "soft structure change" (I've not seen this phrase being used anywhere else before it does seem that it's just Tesco trying to get out of paying people redundancy).
Likewise other aspects such as skilled elements of responsibilities etc will also be taken into account on whether the role is suitable.