I'm still using Win7 at work, (company computer) and it's pretty darn secure.
I doubt that.
Win7 is missing a ton of security features, which are included into win10.
I mean..sure it is not like winXP, which is an open door for every script kiddie, but it is still far away from being secure (at least the individual computer, not talking about your network since i don't know what your protection there is).
We have a robust anti-malware and anti-virus suite with hard-drive boot encryption that helps keeps the systems secure.
Just a question out of curiosity, does your company do regular penetration testing ?
Whenever i see Win7 computer in a company (working as an IT security consultant), there almost always is a misconfiguration which allows lateral movement. And in a terrifying amount of cases it is possible to get domain admin privileges.
And in case of a malicious cleaner/trainee (which are some test cases in my company), win7 computer mostly won't resist attacks. Once an attacker is inside of a network, win7 computer are the #1 target (besides XP which can be found from time to time too).