Damage / Dent on the seat tube.  Please see pictures

Reynolds 531 tubes, Gipiemme dropouts

size:

• seattube C-C 52.5 CM 
• seattube C-T 54 CM 
• toptube C-C 55 CM 
• rear spacing 126mm 
• seatpost size 27.2mm 
• english bottom bracket 

Would make a good restoration project.