Classic Mini brake hose and clutch copper washer. 
These copper sealing washers should be replaced every time the hoses are undone as a precaution. 10mm i/d, 15mm o/d.
This type of washer is also used on Classic Mini and Moke cars as follows:
Clutch & Pedal Linkage - Qty 1  
Single Line Brake Pipes - Qty 1  
Diagonal Split System with 4 way Failure Switch-E - Qty 1  
Brake Pipes - Front to Rear - Qty 1  
Clutch cylinders and flywheel case - Qty 1 
Brake Pipes - Front to Rear Split 1985 on - Qty 1 
(MWA233220A).