On the 1911 census.com (official site of the National Archives) it says
SEARCH FOR FREE
Search the whole census to add vital branches to your family tree
See transcribed details of your ancestors and the original census images
Find out where your family lived, who else lived there and what jobs they did.
PAY TO VIEW
Once you are sure of the record you want, you’ll need to register and buy credits (see left) to view and print and save a typed transcript or an image of the original handwritten page.
Only you can't actually Search for Free like it says. I have searched on my ancestor, and found a summarised entry - name, age, district where they lived, but to look at the original images and find out things like address, I have to pay.
1911 census person search Your search has returned 1 result.
Search criteria used:
County : London Last name : Jackson
First name : Wilfrid Year of Birth : 1881, plus or minus 2 years
Birth place : London Searching within : Households, Institutions, Vessels
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Household Original Census Image
Household JACKSON, Wilfrid H 1882 29 M Wandsworth London VIEW VIEW
If you click on View Household it says - 10 credits unless you have a subscription
If you click on View Original Census Image - it says - 30 credits unless you have a subscription
Cost:
You will be charged 10 credits for a transcript and 30 credits for an image, unless you have purchased a subscription for this set of records
So why does it say you can view this stuff for free, when you can't?