We don't like to tell other trades how to do their jobs but we do sometimes wonder if people know what they're doing. This was a classic invasion of rats making a warm and comfy home in the loft. By the looks of it the pest control "expert" couldn't be bothered to climb into the loft so left all the traps and poison next to the hatch and threw some to the edges.

Maybe he was protecting the rats from the humans?

On inspection, the rats were nesting under some furniture on the far side. I suppose you get what you pay for and maybe the pest controller was cheaper than the other quotes. When dealing with pest control problems hire an expert and not an opportunist.