[spoilers] Departure of Grid Members?

[nothingisasitseems]

I believe the following actors were written out of Spooks as they decided not to renew their contracts:

Matthew Macfadyen (Tom)
Keeley Hawes (Zoe)
Rupert Penry-Jones (Adam)
Hermione Norris (Ros) twice
Richard Armitage (Lucas)
Sophia Myles (Beth)

Does anyone know if the following were written out at the "whim" of Kudos or whether it was their own decision?

David Oyelow (Danny)
Shauna McDonald (Sam)
Rory McGregor (Colin)
Raza Jaffrey (Zafar)
Olga Sosnovska (Fiona)
Nicola Walker (Ruth) - departure at end of Season 5
Alex Lenipekun (Ben)
Gemma Jones (Connie)
Miranda Raison (Jo)
Hugh Simon (Malcolm)
Shazad Latif (Tariq)