We've seen this location before, and the problem for us is that GSV is way out-of-date, once you drive in (virtually of course !!), the last trip by the GSV camera van was 2015 at the entrance to Hanover Avenue: -
https://maps.app.goo.gl/Acgsjj2gZdWnE3yJ8and no "Permit Zone"signs are present.
Normally, for Permit Only parking, visitors can obtain a day permit from the resident being visited. These can be either paper-based scratch-out cards, or virtual ones obtained using the council website.
So, were you visiting anybody on that street ?
The street directly opposite Hanover Avenue has a later GSV view of 2022, in which one can see it is virtually all permit bays, but individually signed. Clearly the attractiveness of this area's location to the Docklands Light Railway station West Silvertown, plus bus services on Silvertown Way was too attractive for commuters wanting free parking, so daytime parking restrictions have been imposed. In London, if unrestricted and free parking seems too good to be true, then it IS too good to be true.
Here is the relevant regulation concerning service of a PCN by a CEO: -
https://www.legislation.gov.uk/uksi/2022/71/regulation/9/made