I spent alot of time and effort in the 1990s, along with many other family historians, campaigning to release the 1901 census early. then the 1911 was on limited release prior to it's statutary release, you can pay to have a search of a specific address for 1921 and no doubt there will be a campaign for it's general early release, mainly based on the early releases of the previous returns but also to bring the England & Wales releases in line with the returns of the US census.
and yes, when the returns were taken they were subject to 100 years closure, and this has been reversed to some extent with the 1911 and so a president has been set.