Pros
Payment rate is good compared to other companies.
They still give work to self employed professionals (outside IR35), something that is rare in UK nowadays.
This company would be good for a worker/labourer that would like to have a serious career. They can grow, even become directors, and they won't have to deal with any sort of harassment. Workers in this place are well respected,
Cons
The below are based on my experience and are just a personal opinion.
The company suffers from a culture of favoritism and office politics. Job security often depends more on personal relationships with higher management than on performance. This creates an unstable and unprofessional work environment where decisions feel arbitrary and employees may experience bullying or a lack of respect. There are no clear HR processes to handle conflicts fairly.
The place might come across as a very bad place for engineers particularly. The projects are run by the Foremen and Works Manager. Roles such as "Senior Project Manager", "Project Manager", "Agent", etc. are purely cosmetic. The Senior Project Manager is working at best like some sort of a Sub-Agent, then the Agent and Sub-Agent are working as a mix of Section Engineers and Site Engineers, then Section Engineers, Senior Engineers, Site Engineers, are all doing exclusively setting out, without any other responsibility whatsoever.
I would not recommend this company to those looking for a transparent or supportive workplace.
I would not recommend this company to anybody with engineering background because it's a career suicide.