As the results are based on vacancies of funded positions it wouldn't be possible for them to have a surplus.
Feel free to check out their workings here *warning* may contain factual based evidence
https://www.rcn.org.uk/professional-development/publications/pub-006195
Results
One basic way to calculate the total number of vacancies across England is to use the whole figure from the 76% data return and, using the average, scale up from trusts who reported 30,224 registered nurse vacancies. This crude method provides a total of 39,603 nurse vacancies. The total band 5-8 nursing funded establishment figure provided was 272,228 and the total band 5-8 vacancy figure was 30,224 giving vacancy rate of 11.1%. When the total funded establishment figure is scaled up based on the response rate, we estimate this to be approximately 337,500. We also looked at two other approaches, scaling up the 76% data return to a whole figure by using the average based on Trust type. We also did this by Health Education England region. Details are provided in the two tables below. This provides a range from 38,901 to 40,958 registered nurse vacancies, respectively. Based on the consistency of the results of the three different methodologies we are confident that as of 1 December 2016 there were approximately 40,000 vacancies of registered nurses in England.