Letts's Diary for the year 1926 recording day-to-day progress by the Resident Engineer's Office on structural reinforcement work on the Dome during 1926, to the recommendations of a Commission of Architects and Engineers. The diary ncludes information on in-letters and out-letters in consultation with experts, contractors and consultants. Also includes notes of drawings made for the work undertaken and deliveries of materials. Many pages initialled by Lt Col Sankey.