The short answer is: we don't know.
The long answer: Newstead don't reveal the real score so we don't know. DD was typically getting about 90% in sample tests by the end of the summer holidays and she did well enough to get a score that was comfortably above the offer day score but certainly wasn't in the 270s either. Whilst she was doing consistently well in practices the odd random test she would get 75% so I think in the real test she needed wriggle room for nerves and unexpected errors. Also some tests seem to suit some children better than others. DD did much better in the Bexley test (CEM) than she did in the Newstead test as I think the style of test suited her, so it is very hard to compare sample tests with actual outcomes but they can be a helpful indicator and help point you to areas that need work. If you are focusing on Newstead that you are using the GL papers which you say you are doing is good. However I don't know how much having also done the CEM practices may have helped DD in the Newstead test or not. Newstead is the one that seems slightly less pressured on time compared to e.g. Bexley or Kent.
Also to clarify that it looks like the score this year went down to 218 (from offer day score of 223) as per this thread here:
viewtopic.php?f=51&t=57321&start=50