TLDR: you must seek legal advice.
Since you've stated that this is relating to a UK company, it will fall under GDPR as interpreted by the Information Commissioner's Office (ICO).
I suggest you read their guidance on this thoroughly:
And if you're feeling so inclined, you can read the full regulation here:
I'm wary of quoting parts of these pages here as it's possible they could change, check for the most updated information and take sound legal advice!
A couple of key parts of the legislation here are:
It's definition of personal data:
‘personal data’ means any information relating to an identified or identifiable natural person (‘data subject’); an identifiable natural person is one who can be identified, directly or indirectly, in particular by reference to an identifier such as a name, an identification number, location data, an online identifier or to one or more factors specific to the physical, physiological, genetic, mental, economic, cultural or social identity of that natural person;
And (emphasis mine):
The principles of data protection should apply to any information concerning an identified or identifiable natural person. Personal data which have undergone pseudonymisation, which could be attributed to a natural person by the use of additional information should be considered to be information on an identifiable natural person. To determine whether a natural person is identifiable, account should be taken of all the means reasonably likely to be used, such as singling out, either by the controller or by another person to identify the natural person directly or indirectly. To ascertain whether means are reasonably likely to be used to identify the natural person, account should be taken of all objective factors, such as the costs of and the amount of time required for identification, taking into consideration the available technology at the time of the processing and technological developments. The principles of data protection should therefore not apply to anonymous information, namely information which does not relate to an identified or identifiable natural person or to personal data rendered anonymous in such a manner that the data subject is not or no longer identifiable. This Regulation does not therefore concern the processing of such anonymous information, including for statistical or research purposes.
So if you think that the data available would be sufficiently difficult to attribute back to an individual, then it would be considered anonymous information. If however, you think it is possible via any means reasonably likely to be used, to identify an individual with this data, then it is only pseudonymised and should be considered personal data.
For example... consider if is it possible, that the owners of one of the restaurants could take the information given and ask a delivery guy something like: "hey do you remember the order you delivered a month ago? They ordered some X and would have been a man about 30 years old?"
The only real advice anybody should give here is this - you must seek professional legal advice on the matter.