In the case of Asif v Elmbridge Borough Council the Employment Appeal Tribunal decided that it was reasonable for an employer not to offer a redundant employee an alternative job, which became available after a colleague resigned from a post newly created following a reorganisation.
The case emphasises the need for employers to have objective reasons for saying 'sorry, this is not a suitable alternative for you'. The employee may not like the answer, but at least they will understand the decision making a challenge less likely. If however a claim is made, then it can be robustly defended, including using data from the original selection exercise where this is appropriate. If you are in a redundancy situation and require any assistance or guidance please contact firstname.lastname@example.org who will be able to advise as appropriate.