Well the flowers appear to have 5 outer petals and, I think, 5 inners. The mark on the inner petals is typical of nivalis although that's not to say that it could not be something else or a hybrid. I cannot tell if the leaves we can see belong to those flowers or not, which is a great pity because leaves are always very important in making an identification. If I thought it was a cultivar with a lost label then the most likely candidate that springs to mind is one called 'Mrs Thompson'. See here:
http://www.judyssnowdrops.co.uk/Plant_Profiles/Hybrids_Single/mrs_thompson/mrs_thompson.htm But if it is just a find in grenadier 's garden then it is just a find in grenadiers garden, albeit an interesting one because of the extra petals.