Any ideas what type of daisy this is?

These daisies have appeared in the middle of an established lawn.  I initially thought they were going to be Oxeye Daisy and I did harvest some Oxeye seeds a few years ago and have tried to grow them in new areas of my garden and field – it has worked quite well but this is an anomaly. These are clearly different to Oxeye Daisies as they are all single stem without any branching on the stems.  I don't think these are Oxeye Daisies which have just not matured, I think they are something else but I really don't know what.  I have included a comparison with Oxeye to give an idea of size etc. flowers are very similar.  

flic.kr/ps/3UTkMC  

Thanks in advance.

Gav