German Fire Protection Association criticise the handling of the Grenfell inquiry

The German Fire Protection Association have sent an open letter to the London Fire Commissioner, Dany Cotton which criticises the questioning of London firefighters during the public inquiry into the Grenfell tower tragedy.
The full letter can be seen below:
Dear London Fire Commissioner Dany Cotton,
We are writing on behalf of the German Fire Protection Association (vfdb) to you and the London Fire Brigade to express our solidarity and our concern about the Public Inquiry about the Fire at Grenfell Tower on June, 14th 2018, which we follow with interest and amounting worry.
As the fire was a major incident with some media coverage also in Germany we started to follow the investigation of the incident and invited one of your leading officers to give a presentation about the incident at our annual conference which Deputy Assistant Commissioner Richard Mills kindly accepted. We learned about facts and challenges and are convinced that lessons can be learned from that fire also in Germany.
As all documents that have been discussed so far in the Inquiry are public available it became absolutely clear that building regulations were not fulfilled in a very wide range in Grenfell Tower. As building regulations generally are introduced to provide safety for the inhabitants in case of fire and to provide measures for successful operations of the fire service. The consequences of major failures of compliance with building regulations can hinder escape and fire suppression or make them impossible.
We think it is absolutely necessary to be aware of that when addressing actions and decisions which have been made during the night of the fire and it should be kept in mind that the major failing of compliance to the building regulations led to an immense speed in fire travel which was not foreseen and not anticipated.
Only one example for the major range of non-compliance with the building regulations is that the fire could spread via the height of the facade from the flat of fire origin to the roof (about 50 m) in only 20 minutes. Anticipated fire spread would be only from one story to the next in about this timeframe. At the same time the fire could re-enter the building because of the kind of façade construction in every flat directly above the flat of fire origin.
We believe it is indispensable to take these facts into account especially in the current phase 1 of the Public Inquiry where the factual narrative of the events should be the focus. As we understand it the London Fire Brigade started work on the suppression of the fire inside and outside immediately after arriving at scene. At the same time the rescue operations started as well. This all has to be considered under the major challenges of a not properly working fire lift and ventilation of the lobbies, only a single staircase and the extreme fire spread as well as the smoke filling of the single staircase very early during the fire.
Keeping that in mind we observe with increasing irritation the questioning of the London Fire Brigade in the Public Inquiry. As it seems that the questioning implies speculations and assessments which are very inadequate at this time. Especially, when knowing that the London Fire Brigade fire fighters were risking their lives again and again during the night to make the impossible possible.
That is the reason why we strongly express to all members of the London Fire Brigade our solidarity and great respect for the performance and efficiency at the night of the fire as well the during the questioning within the Inquiry which is taken with great calmness and professionalism although questions often seem unaware on the issues mentioned above.
We understand the demand for complete clarification of backgrounds and events during the night of the fire. In our view that should not divert from the real problem of the major non-compliance of the building regulations of Grenfell Tower. Speculations about the actions of the London Fire Brigade are seen to be inappropriate by us.