I have had two answers about the use of the wide pavement at Linden House. The Suffolk County Council officer who replied to my enquiry which included a picture of the area said:
"The highway extends from frontage to frontage (not just the carriageway) and therefore, technically, the police may prosecute those who are parking on the wide footways."
Pigeon, the property company which erected the no parking signs, claim they own the land and have offered to show me the relevant deeds.
I shall now go back to the SCC officer for a further response.