It is a well trodden path that employment tribunals may order an unfairly dismissed employee to be re-engaged. It has also been accepted that the employer's failure to comply results in (not a particularly hefty) additional compensatory award.
The attempt by one clever lawyer to enforce that re-engagement order via an injunction has flopped in The Court of Appeal see Mackenzie v The University of Cambridge.
Lord Justice Underhill swiping the appeal 'over the boundary' commented (para 33):
The obligation is one that the statute does not intend should be specifically enforceable (s117 ERA1996) : the only remedy for non-compliance is the additional award. If that means that it is a rather unusual form of "order", so be it.