Push n Park is common practise at MAN, and I think the airport are setting up a few more 'push n park' stands over the summer.
There's a few benefits to pushing and parking, but the main ones are that it frees up a contact stand that's usually required for another flight, and it allows the aircraft to taxi straight out to the runway when it reaches it's slot time rather than wait for a tug crew to come back, who may not come back, leading to it missing its slot
