Preparing for precipitation

Let's face it, it's going to be a wet Christmas holiday and the year is going to end like it started.

My Basso fitted with Crud RoadRacer guards got the most use at the start of the year and it is likely to get wet again during my attempt at the Rapha Festive 500 starting Monday.  My contingency plan should I have problem with the Basso is the Chinook or the Wilier or the fixed wheel or one of my mountain bikes or the Brompton or the recumbent or one of the many other bikes in my garage.

If one of the other bikes comes out to play and it is precipitating then I'm going to get a wet bum :-)

Or am I?  For a measly £6 I've removed the risk of having a rooster tail sprayed up my backside...