i remember when i had my Tier 1 extension appt 3 years ago and was disrupted due to industrial action. I took holiday from office and went to PEO croydon for my appointment and they said due to strike they cannot process at the same day and asked me whether to leave the passport and docs with them or they will reschedule the appointment. I was a bit annoyed because leaving the passport and docs with them and waiting for the decision is the same as applying by post and paying extra feee.
I asked them to reschedule the appointment and had to take another holiday from work to attend the appointment. I got the extension same day on my rescheduled appointment.
Now applying for my ILR next week and signs of strikes doesnt feel good.
fingers crossed.