Sorry thought you had no idea about what type of lamp fitted that style of 4-pin base..
The 1, 2, 3 bit relates to different wattage lamps having a key-way to prevent the wrong lamp being fitted..
example see the 4 pin G24's part way down this link...
https://www.tlc-direct.co.uk/Main_Index/Lighting_Menu_Index/Lamps_and_Tubes_Index/Energy_Saving_Lamps/index.html
Do you have the old lamp..
or is there any writing on the fitting saying Max 13watt or 18watt etc..?
You can get universal LED equivalents that can fit in either...
https://www.lyco.co.uk/bell-cool-white-12w-led-bld-2-4-pin-gx24q-bulb.html
https://www.lyco.co.uk/philips-corepro-6-5w-warm-white-led-4-pin-plc-g24q-2-bulb.html
But as Murdoch said where possible its better to replace the light for a more common type of fitting..
Guinness