Disclaiming specific gift


I work for one of the residuary beneficiaries of an estate whereby the testator left a garage as a specific legacy to several people. The testator died in Oct 2015 and since then the specific beneficiaries have been trying to sell the garage, even though the Executors not assented it to them. The Executors have also refused to wind up the rest of the estate until the garage has been sold - even though it is a specific gift and its sale should have no effect on residue.

We been informed that because repairs are needed on the garage and because it will not sell for as much as previously thought, the specific beneficiaries are considering disclaiming the legacy. My question is: can they do this? Even though the garage has not been assented to them, does their conduct in trying to sell the garage mean that they have accepted the gift?