This plastering job in 2014, was to apply a modern material called K-rend. https://www.k-rend.co.uk/ a Silicone Scraped Topcoat. That you can apply the the outside of the building, to produce a textured finish. The water repellent surface ensures, a freshly rendered appearance for a prolonged period. The finish is drier and thus more resistant to algae growth and the natural phenomenon of lime bloom.
Similar projects. Glass Blocks in Rendered wall
This silicone range incorporates silicone water repellents as an integral part of the cement based render system. This silicone technology imparts a high degree of water repellency to the render surface whilst allowing water vapour to pass through the render allowing the substrate to breathe.