Fake Machine Gun Corps Badge?

[GMGC]

Folks, I could really use some advice from people who know what they're talking about.

I bought what is supposed to be a genuine WWI Grenadier Guards Machine Gun Corps cap badge from a seller on Ebay, but my spidey sense immediately started to tingle when the item arrived and:

1) It clearly is not the item that was depicted in the online auction images

2) It seems suspiciously shiny and "new" looking for a 100+ year old cap badge

3) There is some kind of red coating on a part of the back of the badge, either over or under what also seems (to me, total noob) like a sprayed-on dark coating, parts of which seem to have cracked, revealing tiny glimpses of shiny new metal beneath--not the kind of authentic patina I would expect to see on a badge made a century ago out of brass.

I don't know if the photos I'm posting will provide enough detail for anyone to render an opinion, but I'm hoping so, because I really need to know: have I been rooked, or does this look like it might be legit? I'm already annoyed at the switcheroo with the photo on the auction site versus the item I received, but I'll be doubly p*ssed (and looking to take appropriate action) if this is a modern fake.

I'm a complete novice in these matters, so I don't want to accuse an honest seller of malfeasance due to my own ignorance, but neither do I want to be screwed out of a not insignificant sum of money. Plus I'm amassing this and other memorabilia in the hope of framing them with a photo of my great grandfather, who served in the 1st Battalion Grenadier Guards and in the Guards Machine Gun Corps in WWI, and I'm voluntarily spending a premium price for authentic medals, cap badges, etc., so I'd like to get what I pay for, both for my own sense of justice, and to properly honor Grampy.

This is the front of the badge that I bought. and here is a photo of the back--not sure if you can see the red paint-or-patina down at the 7 o'clock position and on the tips of the metal attachment loops, but it's definitely noticeable when you hold it in your hand, and to my (admittedly entirely novice) eyes, it just doesn't look right.

I'd appreciate the opportunity to benefit from your expertise, ladies and gentlemen.