It is not Stobart. Flybe have wet-leased a VLM F-50 and it is doing various sectors including on the IOM / Manchester and IOM / Stansted routes and other Manchester routes.
For example, at the moment it is doing the first IOM - MAN sector at 06.30. However, this looks likely to be changing shortly as I have bookings on that 06.30 flight for 25 August and it is still showing as a Q400.
The wet-lease also seems to be for at least 7 months as there have already been some notifications to pax of a change of operator and aircraft as far ahead as 28 February 2016.
I have bookings for IOM - MAN on the second rotation on 10 February (a Wednesday) and MAN - IOM on the lunchtime rotation on 28 February (a Sunday) and have been advised by Flybe that these will be operated by VLM's F-50.
The flown sectors and time-keeping of this wet-leased F-50 can be monitored easily here:
www.flightradar24.com/data/airplanes/oo-vlf/
Hope this helps a bit.
Milleriom