This is a well known problem in Scandinavia too. There used to be two sorts of bulbs: 220-230V and 230-240V. Now they have 230V bulbs. However, as a special item, there are 240V bulbs for buildings with "elevated mains voltage", i.e. close to the transformer. Aren't such available in the UK?
Osrams catalogue lists both 230V and 240V bulbs:
http://www.osram.se/Bilder/PDF/Allm%c3%a4nbelysning/Glodlampor.pdf
