on his premises vs at his premises

Some examples from the web:

• No. But it is true that Customs conducted an unsuccessful raid on his premises?
• Before drawing up the EC declaration of conformity, the manufacturer, or his authorised representative in the Community, shall have ensured and be able to guarantee that the documentation listed below is and will remain available on his premises for any inspection purposes:
• (a) They shall extend to the relevant plants or plant products grown, produced or used by the producer or otherwise present on his premises as well as to the growing medium used there.
• They shall extend to the relevant plants or plant products grown, produced or used by the producer or otherwise present on his premises as well as to the growing medium used there.
• The supplier shall keep records of all occurrences of harmful organisms on his premises and of all measures taken in relation to such occurrences.
• when the dealer keeps animals on his premises he shall ensure that:

Some examples from the web:

• 1. When the goods arrive at his premises or at the places specified in the authorisation, the authorised consignee shall:
• When the goods arrive at his premises or at the places specified in the authorisation, the authorised consignee shall:
• Following an application by the consignee, the customs authorities may grant him the status of authorised consignee, thereby authorising him to receive at his premises or at any other specified place goods transported under the TIR procedure.
• 1. Following an application by the consignee, the customs authorities may grant him the status of authorised consignee, thereby authorising him to receive at his premises or at any other specified place goods transported under the TIR procedure.
• The authorized consignee shall, in respect of consignments arriving at his premises or at the places specified in the authorization:
• In respect of goods arriving at his premises or at the place specified in the authorisation referred to in Article 454a, the authorised consignee shall comply with the following obligations, in accordance with the procedure laid down in the authorisation:
• 1. In respect of goods arriving at his premises or at the place specified in the authorisation referred to in Article 454a, the authorised consignee shall comply with the following obligations, in accordance with the procedure laid down in the authorisation: