My first thought was a bucking transformer, one with a 12v output would work for to drop 240v to 228, thus bringing it into line with 230v bulbs.
Normal low voltage lighting transformers may or may not have the required primary to secondary voltage withstand and insulation resistance figures, but it would be worth looking at.
A simpler solution (more DIY than professional however) would be a dimmer switch inline with the normal switch, somewhere inaccessible, set to drop the voltage to 230v rms or even 220, thus increasing the life of the lamps.
Other possible solutions that crossed my tiny mind were back to back zener diodes, and resistors, both of which would require protection, and plenty of heatsinking, even with a 40w bulb as the load. (dropping say 20v at the current required by a 40w lamp still comes close to 4 watts, which in an enclosed area requires plenty of heatsinking).
Other 'sideways' solutions would involve CFL or LED lamps thus bypassing the problem of filament lamps altogether, and increasing lamp life and reducing the power bills as an addition.
I expect this problem to become more common now equipment is being produced for 230v, although our brethren on the European mainland are probably experiencing longer lamp life due to the same causes.
I suspect that the 'super long life rugged' lightbulbs available a few years ago were in fact merely designed for 250-260v, thus providing enormous life on 230-240v supplies, I suspect the 60w version was in fact a 75watt 250v lamp being underrun. I haven't seen these for a few years now but they may also be a solution.
