Unusual buttoning jacket?

[Jim C]

Hello all,
I have a db jacket which has buttoning that I’ve rarely seen in any photos. It was made by A B Croskin, a tailors in Hull (UK)possibly in the 1930s.
Is it unusual or just no online pictures posted?

 

[Aloysius]

What’s unusual about the buttoning to you? 6X3 is not unheard of.

The odd bit is the notch/step lapel, given double breasted coats take a double breasted (peak) lapel or Ulster lapel. But this was a 60s and later fashion at various points.

 

[Bahabp100]

Double breasted coat