TGWU/Unite Parliamentary Branch

From their website:

Working for an MP is an exciting and rewarding job.

However, at some point you may face exactly the same difficulties as you would in any other workplace – a dispute over your job description, a grievance against your employer or simply the need to put a collective case for improvements in working conditions.

MPs’ staff find themselves in a difficult position in terms of claiming their basic working rights. Whilst legally our MP is usually considered our employer, it is IPSA and the House Authorities who are our de facto employers, setting our pay levels, contractual terms and conditions, and working environment. The establishment of IPSA in May 2010 means that, now more than ever, it is important for MPs’ staff to speak with one voice on all of these issues.

The Unite Parliamentary Staff Branch is the only union representing staff of MPs, in constituency offices and in Westminster. Union membership gives you the right to representation in times of trouble. We have trained shop stewards who will be more than willing to help, however small your problem may seem. Our members also come together to campaign for better working conditions.

Link