Polly was still glued to Harry, though the promise of gnomes and Ella's insistence she looked at Ella as if she was going to say 'really?'. Neville couldn't help a small smile when Ella was bouncing at the thought of finding the gnomes - wouldn't do for everyone to be sad today, especially little girls in a huge garden.
"You're welcome Ella. Just have fun and don't go too far... make sure you can see Pansy or Harry, alright?" Neville didn't really know what was going on, but he could tell that Ella knew Harry.
Looking at Harry, he could tell something was going on that they didn't know about, but Neville wasn't about to give Harry a hard time - he didn't have the energy to even if he wanted to. Harry must have had a good reason for keeping whatever was going on to himself, and Neville was wiling to listen when the time came for Harry to tell them what was going on.