Mr. Stubbs was a local builder played by actor James Appleby, who appears in the episode The Builders.
He was a professional, reliable man, as was his firm. Sybil wishes to use him to spruce up the hotel, but Basil hires the cheaper – but totally incompetent cowboy Mr. O'Reilly instead. He does not actually appear on-screen until the very end of the episode.
After several cock-ups Mr. Stubbs inspects his rival O'Reilly's shoddy work, and comes to realise that the hotel is in danger of falling down, and Basil then storms off vowing to insert a large garden gnome in O'Reilly, and then possibly going to Canada.