I won't give too much detail, but essentially I have been seconded into a higher-grade role for the past 2 years, but had been with the company since 2018. Was on maternity leave in 2020 and came back into my role briefly for about 5 months before accepting the secondment. My maternity cover continued performing in my substantive post and last I learned she was made permanent and filled the post. I was assured this won't impact my return to my substantive role after my secondment ends. Now I am being informed that actually it will be a problem and that in effect there is no role for me to go back to because it's already been filled. They are proposing looking for a temporary project for me until I find a suitable role in the company, but if they don't find this for me, then this will go into consultation with the 2 of us competing for my substantive role. My problem with this is that what they have done is surely illegal? They shouldn't have filled my permanent role with anyone else on a permanent basis and now saying there is no role for me to return to? That goes against the secondment policy, which states that this could only happen if there was a reorg, or the role became unavailable, but it's still there - it's just been given to someone else! What are my options here? is the best option for me to get a lawyer and sue them? Any advice would be much appreciated!