Screw type electricity light bulbs.

[BML]

For the second time this week I have bought electric light bulbs with screw fittings when all of my fittings are bayonet. I know it’s my fault for not checking them properly but it’s time to ask a couple of questions.
1. Why are the DIY shops shelves becoming increasingly full of screw fixing bulbs?
2. Is it possible to change my fittings from bayonet to screw fix?

[ericmark]

Edison screw I think came out before bayonet types. There are a number of reasons to use different types of cap. At work all 110 volt bulbs were E27 screw, and 230 volt were BA22d bayonet, simply so we would not make a mistake, but they could be bought either way around. Personally I preferred the BA22d as when they got smashed I could remove the old shell easier.
The smaller bulbs E14 or BA15d again we tended to use E14 for mains and BA15d for cars and wagons, you could buy with either cap, but again is saved mistakes.
The plastic holder for the E14 bulb is I think easier to wire on a production line than the bayonet type, and there is no need to use spring loaded pins to make contact with the bulb, so I think the main reason for moving back to screw is production costs.
I have found a lot of stuff from Europe tends to use the screw type bulb. Except for one odd up-lighter in my house all large bulbs are bayonet type BA22d and again I think all the small bulbs are small Edison screw E14.
I would tend to use the small bulbs in table lamps as the hole is too small to poke a finger into in error. Although not to the 12.5mm of a standard finger. You however can get bulb holders where until the pins are pushed in they are not live. I considered tell my kids not to put their fingers in the lamp holder was enough. Although I do have RCD protection on all circuits.

[BML]

Many thanks for your very full reply.