HO
Which only leaves Emily and Gavin on those days, both of whom have other responsibilities. If Mishal had become a new Newsnight presenter the BBC would have announced it, and I somehow doubt they'd put any presenter on for such a long run before confirming them as a permanent presenter. It's more likely none of the current team want to or can do Fridays for a while.
Does Kirsty present the Review Show often? If she does then this reduces how much Newsnight she can present considering it's from Scotland - possibly takes out Thursday and Friday.
Which only leaves Emily and Gavin on those days, both of whom have other responsibilities. If Mishal had become a new Newsnight presenter the BBC would have announced it, and I somehow doubt they'd put any presenter on for such a long run before confirming them as a permanent presenter. It's more likely none of the current team want to or can do Fridays for a while.