Technical Booklet E Fire Safety·Page 172·6.21J
Secure information box provision requirement
Buildings containing flats with a top storey more than 11 m above ground level must be provided with a secure information box.
A building containing flats with a top storey more than 11 m above ground level should be provided with a secure information box.
Source — /Users/richardhill/Documents/planning-arch-project/data/documents/regional/Technical Booklet E - Fire Safety.pdf