I know using the 50W lamps is wasting energy but throwing them away is too. However, they were use four at a time in the fittings we have in each room, that 200W just to light the lounge, reusing theses lamps one at a time isn't too bad! I reckon my supply of pre-used lamps should see me OK for the next twenty years. These adapters are also available in ES (Edison Screw type). You could, if the fitting allows, use them to put LED spot lamps in your favourite retro angle-poise! When looking for these adapters use the terms "BC to GU10" or "ES to GU10 adptors".
73 Rick G6AKG