Jason as Betty says the unbranched flower stems point to this being R. gratiticola, but Mulligans Flat is a disjunct location from all other ACT records that are in Namadgi. Can you please go back and pull a petal off a flower and take a photo of the nectary lobe at the base which is another key ID feature. What we are after is a photo like thishttps://www.flickr.com/photos/22616984@N07/5130401981
Thanks Jason , as the nectary is wider at the top this id's it as Ranunculus lappaceus, which for some reason has decided not to branch its stems out, maybe it feels secure enough inside the fence at Mulligan's Flat