So I posted a month ago about the police suspecting me of growing cannabis due to the tinfoil light-proofing over my bedroom windows. Among the responses to that was one from shermarama, who pointed out that hydroponics shops will actually sell you reflective plastic sheeting designed specifically for keeping light in or out, and that this might work better than tinfoil.

In fact the tinfoil, although the best idea I had yet come up with, is not terribly easy to work with due to tearing very easily. I made a couple of biggish holes in it when I put it up, and then there were an enormous number of pinpoint holes which it seems to have been gradually developing over a year by no terribly obvious mechanism. So at the weekend I placed an order over the Internet, and yesterday I celebrated the summer solstice by taking down my ad-hoc tinfoil and replacing it with proper blackout sheeting designed by professionals.

The same shop also supplied a 50m roll of light-proof metal foil tape to fasten the sheeting with. This impresses me in particular because I'd previously bought metal foil tape from Mackays who charge several pounds for a three-metre roll; I had assumed the high price was an unfortunate consequence of the nature of the stuff, but now I've bought 50m for under a tenner I suddenly believe Mackays' price to be an unconscionable rip-off.

Actually putting the stuff up was surprisingly fiddly. The most difficult bit was cutting the sheeting into the right size pieces, because it's so big (I got a 2m × 5m piece) and staticky and slippery that it's almost impossible to lay it out flat and measure right angles and distances on it. I think I know how I'd do it better the next time (start by measuring all the pieces you're going to need, work out the smallest rectangle of sheeting you can cut all those pieces out of, cut that rectangle off the main sheet and then you might have a fighting chance of opening that out flat for subdivision), but this time was quite a pain.

But once you manage to get the stuff up there, it works extremely well; I recommend it. Definitely better than any of my previous solutions. My windows are still not perfectly light-proofed (the main source of leakage is now crinkles in the metal tape where I put it up incompetently), but I've now reached the point where more light is coming in round the bedroom door than through the windows by a full order of magnitude, and that's more than good enough.

And now I've got reflectively covered windows, high electricity bills (well, in winter at least) and a paper trail linking me to a hydroponics shop. The search warrant can surely only be days away :-)

Last week I posted a lateral-thinking question and promised to follow up with a list of the responses I'd got when I previously ran this question in 1998.

Here were the 1998 answers:

• Become the Enemy (Amf)
• Build a third fortress inside the inner one (lovelyoliver)
• When the Enemy get in, show them a big bomb for which you're holding down a dead-man switch, and strongly suggest they go away again (lovelyoliver)
• Call on the power of Satan (lovelyoliver)
• ‘I'd read that the best weapon was the element of surprise. So I started to beat myself up.’ (drswirly; originally from a Paul Merton sketch)
• Perform an inversion with respect to the inner fortress, and then lay siege to them (drswirly)
• Cause the inner fortress to levitate and run away to elsewhere (bjh21)
• You shouldn't have built weapons that can point inwards as well as outwards in the first place (jaylett)
• Fill the gap between the inner and outer walls with glue (stephdiary)
• Flee through a trapdoor or tunnel (cowe and Brock, independently)
• You still have the tactical advantage that you know their new weapons intimately and they don't (cowe and me, independently).

This year's responses seemed to put much more of an emphasis on telling me I shouldn't have got into the situation in the first place; there were a lot of things like ‘of course you booby-trapped the weapons before retreating’, ‘revoke the firing codes for the weapons’, ‘broadcast the self-destruct codes for the weapons’ and ‘you're doomed anyway so you might as well sit down and have some tea and cake’.

Also various people dealt with the problem by positing facts which simply made it not a problem: you might have run out of ammo, for example, or the enemy might be too stupid to use the weapons anyway. Two people independently pointed out that siege weapons and anti-siege weapons aren't the same thing (the former are anti-structure whereas the latter are anti-personnel) so the enemy might simply not have had much use for my weaponry after all. Notable in this category was damerell who suggested (as he put it) a large-corporate answer: the reason we lost the outer fortress in the first place was because none of the heavy weaponry ever actually worked or it was more dangerous to the operators than to the targets, and so if the enemy tries to use it all we have to do is sit back and have a laugh.

cowe had the new and entertaining idea of hiding all my valuables in one of the outer weapons before retreating to the inner fortress, presumably in the hope that the enemy would get into the inner fortress, ransack it, find nothing and go away again.

mooism suggested escaping by means of an enormous catapult, which I'm frankly astonished nobody thought of in 1998 given that at the time my social group had a running in-joke all about enormous catapults. He also suggested calling on the UN for help, which I suppose is a better bet than Satan. Maybe.