He bided his time, waiting until Peters rose to question the Prime Minister about claims that passengers arriving on China Southern Airlines are being fast-tracked through border security.
Like a dog with its head down a rabbit-hole, Peters had been so consumed with challenging the validity of John Key's replies that he did not notice the figure five rows behind him was about to upstage him.
"Does the Prime Minister agree that natural justice and due process are relevant in the administration of the Immigration Act?" Horan asked Key, ensuring his query sounded relevant to the original question and so could not be ruled out of order.
Horan's question had nothing to do with the Immigration Act and everything to do with the apparent absence of natural justice and due process with regard to his expulsion from NZ First.
The Prime Minister obliged by replying that natural justice was important - as was consistency. Key then had a further go at Peters by contrasting the challenging task of handling 170,000 visa applications from China each year and managing a caucus with just eight members.
Peters responded by pointing out that Key's handling of Act MP John Banks had been flawed. But it was too little too late. Horan's ambush had secured him a minor victory over his old boss.