Redtail - the largest 'unionised' Engineer workforce in the UK industry is at BA, & some guys there work 7 on, 3 off, 7 on, 4 off, earlies & lates!
Some loons even like it! (back in Airtours/BOAC/BEA days etc etc ramble ramble types).
All for having a union tho' , just so long as it's the right one.