"Bird flu? BIRD FLU!?" says Matthew when I put my assumptions to him. "What precisely do you think I am going to do?" He is melodramatically fanning himself with the weaponry brochure as if the sheer lunacy of my suggestion is making him feel faint. "Do you imagine I am planning to sit on the veranda picking off passing sparrows?"
"Starlings," I said.
"No, not even starlings," said Matthew. "In fact, the only bird victim I have in mind is the one that sits outside my shed impersonating the sound of my phone ringing."
"So are you going to shoot that then?"
"I would like to, but no, I am not. In fact I am not going to shoot anything. You are. The airgun that I am about to order is for you. I am putting you in charge of shooting the mouse."
Matthew first spotted the mouse in the sitting-room a fortnight ago. It came out of the fireplace with, he said, "unnerving insouciance". I suggested we put down traps, but Matthew came over all Buddhist and said that until the mouse did something seriously bad or immoral, or invited its family and friends in, he couldn't bear the thought of killing it.
The other factor determining the fate of the mouse is the memory of the terrible stench of rotting rodent that results from getting the council out to put poison down. It is a smell that takes weeks to fade and the last time, when we had a major infestation, I spent a fortune on scented candles and joss sticks, some of which, Matthew said, were very similar in odour to the little rotting corpses lying out of reach under the floorboards.
Then suddenly, last weekend, Matthew started playing hardball with the mouse. He said that while he hoped it wouldn't suffer unnecessarily, it must die. I was staying with a friend in the country when he rang to tell me this. He reported a sighting in the bedroom. "I am sure it is the same mouse," he said. "It's following me. It's a stalking mouse. It knew I had left the remains of a Domino's pizza on the floor and it can only have had that information if it had been carrying out scrupulous surveillance."
Two more nights passed, and when there was no sign of the mouse Matthew started to worry for its welfare. He was on an emotional roller-coaster. But then on Wednesday he swung violently back towards the hard right after discovering some nibbled Bendicks Bittermints.
"I'm sorry," he said, "but I cannot and will not tolerate interference with my Bendices." (Matthew is a stickler for the correct plural.)
It was then that, standing in front of the fireplace from whence the mouse had first ventured, he finally and most emphatically pronounced sentence of death. His hands were behind his back and his head was held high. There was no doubting from his grave tone that this time there was to be no reprieve.
It is I who must fire the gun because Matthew is too squeamish and has become too well acquainted with the mouse to pull the trigger himself. I, however, am refusing to become a one-woman rodent firing squad largely because I have no shooting experience and am liable either to take out the carriage clock or merely wound the mouse, leaving it to die a slow and agonising death. Matthew says that until I do shoot the mouse he will be in his shed, which appears to be mouse-free.
I have been trying to phone him there to give him the news that what I intend to do is catch the mouse in a humane trap and then set it loose on Shepherd's Bush Green. But he is not answering. This is because every time the phone rings he thinks it is the bird outside his shed, so he leaps out of his chair and bangs his umbrella violently against a nearby tree, shouting: "Don't think I am so easily fooled, you varmint! Why don't you clear off out of it!"
I am watching all this from the sitting-room window and it passes the time. From the rustling noise behind me I would say the mouse is nearby, possibly nibbling on a Quality Street. If I did have an airgun on me now I could probably hit it. I could also get, one by one, all of Matthew's pipes in their pipe-stand, which is strangely tempting.
The phone-impersonating bird, or rather the ever-ringing, unanswered phone, has driven Matthew back into the house, and he has now agreed to catching the mouse and setting it free, although he is quite cross about the Quality Street. He has given me a two-week window, and after that, if the mouse is still with us, I will be handed the airgun, with the words: "I think you know what you must do."
So I am off to the hardware shop to buy humane traps, and Matthew is attempting to get in touch with Bill Oddie. He says he wants to know if there is such a thing as an avian laryngectomy.