57689 Fuel Pipe Clamp Blocks for RHD DB2 to DB MkIII models  1950 to 1959, these aren't the same as DB4 to DB6 Pipe Clamp Blocks as the pipes are larger on those models 

Comes as a kit with 2 halves, 1 bolt, 1 nut, & a Stainless Steel Reinforcing plate,, the ones shown in the photo are for the brake pipes but its the same except for the pipe hole size