That could be a problem, however I am *not* an expert on copyright and licensing. OSM's Licensing Working Group may be able to clarify if you are unsure.

https://wiki.osmfoundation.org/wiki/Licensing_Working_Group

The Greater London Authority release a lot of open data under OGLv3, but this does not appear to apply to the whole london.gov.uk site:

"The site contains copyright material, trade names and other proprietary information, including, but not limited to, text, photos, graphics, video and audio. The entire contents of the site are protected by copyright law. We, or our licensors, own copyright in the selection, coordination, arrangement and enhancement of such content, as well as in the content original to it."

https://www.london.gov.uk/terms-and-conditions/terms-and-conditions-use-our-website-and-talk-london-website