There are very few reliable gun stats online. It's something I discovered a few years ago in a similar conversation. BTW, it's not poisoning the well, if anything it's ad hominem fallacy as I discussed the credibility of the source, but really it's not a fallacy at all to question the validity of unsubstantiated stats from a gun enthusiast site about gun control. It's perfectly reasonable.
According to a UK Gov website,
less than .05% of all crime in the UK is linked to guns.
The gun ban started in 1997. What do you see between 1997 and 2000?
Crime did go up 35% in 2003, but that was attributed to drugs, not guns. Gun crime is still VERY low.