The advising and arranging of an endowment mortgage do not generally constitute a necessary part of the conveyancing transaction. However, if these activities are complementary to the primary conveyancing services provided by the firm, FCA authorisation is not required. The 'necessary' exclusion would not apply here, but the activities are permissible without additional authorisation if they are seen as ancillary to the main legal services.

Key Point: This question tests the application of the 'necessary' exclusion and when FCA authorisation is required for advising and arranging financial products in the context of legal services.