Having an affair with a colleague has been ranked top of a list of seven deadly business sins by leadership consultancy First100.

The firm has compiled the following for new starters:

1. Don’t sleep with a colleague (unless you are married or in a relationship with them);
2. Don’t keep referring to “how we did things in my old company”;
3. Avoid too many introductory meetings which you can’t follow up;
4. Don’t make decisions just for the sake of being decisive;
5. Don’t avoid sacking someone in the hope they’ll work out – they rarely do;
6. Don’t avoid playing the political game – everyone else is at it;
7. Avoid telling staff you’re going to spend your first 3 months asking questions