Complex sentence: This last had been severely compromised when 16 columns had been removed to build the new school chapel in 1926, these were re-carved and the building re-roofed at the cost of £1,300,000.
Split into simpler sentences: This last had been severely compromised when 16 columns had been removed to build the new school chapel in 1926. Replacement columns were carved and the building re-roofed at the cost of £1,300,000.