Take two straps and run them over the bottom yoke and pull them forward. Take a further two and put them through the frame where it goes back up towards the seat.
You should be able to shake the bike and feel the trailer move not the bike, because the suspension is under compression.
I only ever use two straps on mine. Taking one through the trellis just where it bends in to the front of the bike each side. Ratchet down tight - Job Done
Thanks for the comments folks. We got it back safe and sound, the only issue is Mrs R has taken a shine to it and has no been comandered. Cheers Allan R