Another what is it

[Anguz]

Obtained by a mate
3/4 to 1/2 adaptor with a weird 3/4
What was it's intended purpose?

 

[Erie Fred]

Factory defect ?

 

[Anguz]

if it is, we have 2 identical

 

[cheb]

An organisation specific shape to cut down on theft maybe?

Like the strange 13A plugs and sockets that turn up occasinally.

 

[Erie Fred]

if it is, we have 2 identical

Again. leaving out pertinent information in the OP.
GiGO

 

[meyrickt]

Adapter for a torque wrench. 1/2" to 1/4"

 

[Redsailor]

Possibly designed to fit a specialised tool or wrench and shaped so that some monkey doesn't use a 3/4" breaker bar on it. That's my guess ????

 

[Anguz]

same part number as a standard one though

 

[brightspark]

Again. leaving out pertinent information in the OP.
GiGO

gigo =garbage in garbage out

 

[Welderpaul]

Googling Britool EPHS brings loads of these up, but none have the corner as per yours. Strange.

 

[Dozzer]

As others have suggested, to be used with the right 3/4 tools and to stop the use of air impacts etc?
Looks like the corner has been intentionally filled, not factory?