It is only the gf and I who are here, togther with her three dogs. She isn't very bothered by the rat snake and it is her job to go and cut that lemongrass near the snake's hole when she needs it.
On the plus side, I haven't seen any rats around here.
Maybe now the grass is cut it the snake will move on. Unless that big hole is a nest. I'll give it some time and see what happens. If it is unfriendly then I'll tell the neighbours - old Isan farmers, that snake will be straight in the pot.