Hhhhhmmmm. A Nellie in my garden gets very pollinated, and I'm 99% sure there are no Burfords around. (it was planted by prior owners, not a holly I would collect) So does something else pollinate it? About 100 ft away is an 'Ajax'. I suspect Nellie can be pollinated by a variety of Eurasian male hollies.

Always have lots of berries on my Nellie, but it may be pollinated by Oakleaf, or Sled Run.

Nellies are highly self pollinating, more so than any holly I've ever seen. They have female flowers, male flowers, and hermaphroditic flowers on the same plant. If your mature plants are low on berries, I'd wonder if you should investigate the insect side of the situation. In some locations, bees have all but disappeared.

Edward J. Stevens is the "husband" of Nellie R. It's not easy to find, mostly because Nellie simply doesn't require him to make berries.

She/it/they can also be pollinated by any Ilex cornuta male with simultaneous flowering.......not that it is particularly necessary :-)

Gardengal, I'm glad we've clarified Nellie's pronouns. ;-)