Introductory flights originate from Germany. Where there groups of PPL's that owned an aircraft, but miles away from an flight school. So they allowed in Germany ppl holders to introduce potential members to flying by taking them up and getting them to pay for the flight. So that person doesn't have to travel miles for a trial lesson. Initially it wasn't allowed under EASA, but later added.
Flight schools in the UK are abusing it, by getting ppl's to do trial lessons as introductory flights. Not paying the PPL holder but also not reducing the price compared to a trial lesson. Generating more money for the flight school and reducing the flying for instructors.
Leading Edge is not an ATO but an RTF.
Part of it hangs on the caa's definition of marginal activity:
The term marginal activity should be understood as representing a very minor part of the overall activity of an organisation, mainly for the purpose of promoting itself or attracting new students or members. An organisation intending to offer such flights as regular business activity is not considered to meet the condition of marginal activity. Also, flights organised with the sole intent to generate income for the organisation are not considered to be a marginal activity.
I think if you are selling these flights on your website according to this definition it's not a marginal activity any more.
CAA is not interested in enforcing this, I have seen an email from the CAA to the school in question stating that no guest control is allowed below 500ft. That would suggest that the CAA is okay with guest control above 500ft which would go against the ANO and EASA law.
It's a race to the bottom, flying is too expensive so schools are trying to reduce costs by reducing instructors pay. Getting an instructors rating is useless, no way you will get a return on your investment.