(I've namechanged for this as this as potentially sensitive)
I have been given notice that I am potentially redundant.
For various reasons, I fully believe the real reason for my redundancy is that I'm a PT working mum - but I will never be able to prove this.
However, when the reasons for redundancy were explained, one reason given was 'During [period of my maternity leave] we did not have a full headcount yet still covered the work needed'. In other words, I went on maternity leave, they didn't replace me (except for a few outsourced projects to a freelancer) and decided they didn't need me any more. They also stated that they started to put the case together for redundancy during the last part of my maternity leave. I have been back at work several months so obviously don't have any protection of still being on mat leave.
Is this legal? I suspect it is, but am 

beyond belief and feel like I've been penalised for taking time off work.