Last winter CWL also seen a lone divert of a Stanstead or Luton based Ryanair aircraft. I believe that CWL is not a preffered alternate for Ryanair however it is still used occasionally as demonstrated last night.
There maybe an added factor of wx conditions at BOH possibly worse than CWL providing a better option or could it be one of the ex CWL based WW captains who are more familiar with the CWL facilities.
Same can be said on the 2 x Flybe diverts into BRS rather than CWL as has happened in the past but in all fairness if technical assistance is required then EXT is closer for the engineers.