It is the cost of administrative processing by the court or public institution and the tax that can be seen as evidence of administrative processing. It's a similar role to the stamp used to send letters. This is a charge regardless of whether or not a solicitor is appointed.

You can use the 'Registeration Cost Calculator' to calculate not only solicitor fee but also the costs required for the acquisition and registration of real estate, such as acquisition tax, national housing bond purchase and discount, and court fees and so on.