I was told that as a ‘return to work mum’ I would not be eligible for a promotion

I worked in a well known university for two years before I fell pregnant with my first child.
The programme was in serious financial difficulty for the duration of these two years – as such I worked 12 hour days to build and develop the profile for the organisation to receive more funding, visibility etc.
I devised a strategy with the senior leadership to diversify our research field into other programme areas in order to survive – I worked hundreds of extra hours to make this possible.
I went on maternity leave during which time I had a maternity cover who I hired and supported extensively to take over my role (I stayed an extra week before the baby arrived to handover, I wrote the strategy and yearly plan for her etc.)
During the end of my maternity the new position – which I had created – came up. It was
a more senior version of my role looking after the existing and new programmes.
When I asked to return part time, and developed a business case to extend the team size to cover (at a lower cost) my part time reduction in hours it was made quite clear that as a return to work mum unless I was prepared to work full time I would not get the role.
My maternity cover got the role and then became my manager.
She took over all the interesting parts of my role, took away half my resources and never looked back.
Some women will do anything to get ahead, even those who have had children themselves.
My employer showed no loyalty for the work I put in to keep the organisation afloat.