If the Solicitor's firm that drafted the will included the provision that their firm be used, that may potentially put them in a conflict of interest scenario.
However, as far as I can see (and I've looked), there does not appear to be any express legal or ethical bar on such a provision being put into a will. The general rule for solicitors is that a solicitor should not draft a will where he is the recipient of a gift or bequest under the will. The ethical guidance states that it is prudent for a solicitor to refuse to accept any benefit under a will he/she is personally drafting. All that said, I would not have included such wording if I was a Solicitor drafting a will which I was ultimately seeking to benefit from.
Nonetheless, whilst the Solicitor who drafted the will from which s/he seeks to benefit may encounter ethical questions (in the event of a complaint to the Regulator) as to why such wording was included, this does not invalidate the will and nor does it remove (in my view) the obligation on the executor to adhere to the will's provisions. We are not even sure here whether the firm who drafted the will is the same firm named in the will. As pointed out earlier, the testator may have had good reason to name the solicitor's firm, as they may be familiar with the unique circumstances surrounding the estate and the individuals involved etc.
@Thirsty asked some valid questions earlier, which I will now address:
In the end, the OP should seek their own advice on the matter, but the easiest thing is to follow the will's directions. Doing otherwise could end up messy.
However, as far as I can see (and I've looked), there does not appear to be any express legal or ethical bar on such a provision being put into a will. The general rule for solicitors is that a solicitor should not draft a will where he is the recipient of a gift or bequest under the will. The ethical guidance states that it is prudent for a solicitor to refuse to accept any benefit under a will he/she is personally drafting. All that said, I would not have included such wording if I was a Solicitor drafting a will which I was ultimately seeking to benefit from.
Nonetheless, whilst the Solicitor who drafted the will from which s/he seeks to benefit may encounter ethical questions (in the event of a complaint to the Regulator) as to why such wording was included, this does not invalidate the will and nor does it remove (in my view) the obligation on the executor to adhere to the will's provisions. We are not even sure here whether the firm who drafted the will is the same firm named in the will. As pointed out earlier, the testator may have had good reason to name the solicitor's firm, as they may be familiar with the unique circumstances surrounding the estate and the individuals involved etc.
@Thirsty asked some valid questions earlier, which I will now address:
By 'authority', I mean who enforces the use of Jane Bloggs Solicitor? The authority for the executor to act comes from the Will. Ultimately the High Court has authority in the sense that the Probate is a document issued by High Court and has authority in the event of a dispute.
Will the probate office reject an application if it wasn't made by Jane Bloggs Solicitor? The probate office (an office of the High Court) is notoriously pernickety as regards Probate applications and do review the will and probate application documents in some detail to ensure legal validity. However, they are more interested in the legal form of the will and accompanying documents, so they may not object to another firm than that mentioned in the will processing the application. That said, who knows whether they would raise this as an issue.
Can a beneficiary sue if Jane Bloggs is not the probate applicant? Yes, a beneficiary may sue. And it is the executor they would name in the proceedings. Picture this: the executor goes ahead and ignores the will provisions concerning the named solicitor's firm and proceeds to use their own chosen solicitor, who proceeds to make a horlicks of the administration of the estate. The affected beneficiaries will not be shy in those circumstances in pointing out (as part of any contentious litigation involving the executor/their chosen firm) that the executor had acted contrary to the will's provisions in not following the testator's wishes concerning the named firm in the will. This is where the executor could get caught out and may become personally liable.
Can an executor be removed for engaging a different Solicitor? Probably not, but the the executor could be removed by order of the High Court. It's unlikely in my view, unless the executor's chosen firm has acted in bad faith in cahoots with the executor in the maladministration of the estate
In the end, the OP should seek their own advice on the matter, but the easiest thing is to follow the will's directions. Doing otherwise could end up messy.