Hi Joe
If this person was really a member of the public then I agree that it is not reportable for reasons already given.
But, what if this person was there to take photographs (in the course of their employment or SELF-EMPLOYMENT) then different rules comes into play.
Initially it is about identifying the "responsible perons"
Responsible person
3.—(1) In these Regulations, the “responsible person” is—
(a) in relation to an injury, death or dangerous occurrence reportable under regulation 4, 5, 6or 7 or recordable under regulation 12(1)(b) involving—
(i) an employee, that employee’s employer; or
(ii) a person not at work or a self-employed person, or in relation to any other dangerousoccurrence, the person who by means of their carrying on any undertaking was incontrol of the premises where the reportable or recordable incident happened, at thetime it happened; or [continues]
So, if this person was "at work" [as defined in the Health and Safety at Work etc Act 1974] the the responsible person is their OWN employer, or if self-employed whoever was in control of the premises.
That's one of the changes that came in with RIDDOR 2013. Under previous iterations of RIDDOR the self-employed were required to report some accidents to themselves and HSE research indicated that over 90% didn't - not particularly surprising - hardly at the top of your priorities when you are recovering.
Then we have to look at whether it meets reportability criteria for non-fatals to a person "at work".
Non-fatal injuries to workers
4.—(1) Where any person at work, as a result of a work-related accident, suffers— [continues]
(2) Where any person at work is incapacitated for routine work for more than seven consecutive days (excluding the day of the accident) because of an injury resulting from an accident arising out of or in connection with that work, the responsible person must send a report to the relevant enforcing authority in an approved manner as soon as practicable and in any event within 15 days of the accident.
On the basis of your narrative, it sounds as if this WAS reportable as an "over 7 day accident" IF the person was "at work" - if self-employed down to whoever was in control of the site. [All assumes that you are not challenging any element of the narrative]
If it has taken time for the information to reach the "reportable person" and they were to miss the 15 day deadline, the chances of enforcement action for late reporting is very, very slim. The enforcing authorities are stretched and have better things to do than chase late RIDDORs - should be more interested in the ones that are NOT reported at all.
Conversely, if the person was just a member of the public, then NOT reportable.
P