Windows 7 or El Capitan issues

Hi all,

I'm reading mixed views about whether you can install Windows 7 boot camp on El Capitan or not. Some say yes, some say no.

One of my customers bought an iMac with El Capitan installed (10.11.3) and I'm just trying to install Windows 7 Pro (64-bit) through Bootcamp. It errors every time saying "Need 64-bit Windows 8 or higher"

Have tried different ISOs.

Have also tried editing the info.plist file in the Bootcamp contenst package.

But none of these solutions worked.

Mac info is iMac 21.5", Late 2015. version iMac 16,1

Any further suggestions would be appreciated, surely there's a way I can get it installed?

The system is going to run in a school where Windows 8 and 10 are having issues running at present.

Thanks,

Nige