Please note that the London Ultra Low Emission Zone changes that happen in April 2019 might affect your journey to Marshall House by car. These changes directly affect Central London (Marshall House is outside this area) but if your journey passes through this area, you might need to check on the TfL website.
There are further changes happening in October 2021 which will bring Marshall House into the Ultra Low Emission Zone and so will directly affect everyone travelling to MH by car. Again, details are available from the TfL website.