Serious question: is a chainsaw an option for home defence?

Well...so sorry to be reminded once again that you Brits aren't allowed guns. It's a pity. For instance, an intruder used that 2x4 on my face about a month ago (and my dog too)...I didn't have time to get to my .38 special, which I would've used handily. So, I suppose, stick w/ the 2x4. Chainsaws take some priming and a few pulls to get running, and sometimes, one just won't have the time. BTW, are knives legal across the pond? My second line of defense is a matchete.