Patrick Somers, head of legal, who joined Transco six months ago from his post as corporate partner at Irwin Mitchell, says the company instructs the firms on an ad-hoc basis.
Somers says: "The feeling is that there will be two or three City firms on the panel and the same number of local firms."
He says that the review process has already begun. "We have done a review to a certain extent already and we have been talking to firms like Linklaters to look at what it can offer us."
He adds that Transco has been talking to other City players about undergoing a beauty parade.
He says a decision on the panel will be made after the demerger, when the company will also look at its European network, which it is hoping to expand.
Commenting on which firms he will instruct on a European basis, Somers says: "That is the big question. A firm like Linklaters could offer us its European network."
He says it is not guaranteed that those firms with foreign offices will be chosen as he may choose to look to local firms in the various regions.
Although Transco shares its firms with BG and could choose to retain some of the practices both entities use, Somers says he does not think it will cause problems as Linklaters is advising both on the demerger.
He says: "We have got an exceptionally good relationship with the people there."
But he adds: "There may be a potential for conflict and we will expect those firms which are on panel to be aware of the possibility."