I looked at paid storage as there's quite a few of them round here, the cheapest I could get was only around £12 per month which I thought was pretty reasonable for the peace of mind it would bring. I went down and had a look at the location in the racking and it looked safe enough and probably out of harms way.
The thing that put me off was hours of access though, most of my trips involve me getting loaded up and on the road at some ungodly hour in the morning, especially if I'm heading north for two or three nights. To get my boat I'd have to arrange to collect it the previous night and then have it at home over night, since we've had the hall and stairs redecorated there's no way Carol was going to stand for that.
Have a ring around though I expect the firms will have different policies and you might find one to suit Dave.
Local council garages are worth a look at too if they're in a decent spot, unfortunately the ones near us are where the chavs and smack heads hang out so I didn't fancy it.
In the end I decided to knock this up in the garden ...
I made a c-shaped bar from 2x2 which slid in behind the seat and thwart and then padlocked onto the horizontal bars. Not bombproof but enough to keep them busy while I get the rifle loaded
I've changed my wee Pack for a 15 footer now so I've had to add some girth to the rack but I've also added some u-bolts to that wall which I can put some chain through at the ends of the boat. That way it can't be slid out even if they do trash everything else in the process.
Depending on what boat you're after Dave you could even get it in the house somewhere, Grooveski had his Pack on top of a wardrobe in his flat for a good while