Honda 2.3 plug spanner size

[eddystone]

When I bought this second hand it came with a toolkit but the plug spanner does not fit - any idea correct size?

 

[Momac]

Does the spark pug have a letter/number code on it , which might help identify the dimensions ?

 

[VicS]

When I bought this second hand it came with a toolkit but the plug spanner does not fit - any idea correct size?

5/8" ( 16mm ) AF
See the owners manual for the correct plug type for your model. plug gap and torque when refitting

( Maybe the spanner you have is for the oil drain plug so don't chuck it)