totti highflyer, you're right, it really is as simple as that.
Just for clarity, the Q400 checklist will lead you into a decision making process in the fact that if it is serious enough it will instruct you to "land immediately at the nearest suitable airfield" or "land at the nearest suitable airfield". Notice the slight difference.
This incident happened around 10:50z, the weather in the South and West of England at the time was not pleasant.
Guernsey - R09/27
EGJB 081050Z 18021G33KT 9999 -RA SCT012 BKN022 13/12 Q1000
EGJB 081120Z 19023KT 9999 VCSH SCT013 BKN025 14/12 Q1000
Jersey - R08/26
EGJJ 081050Z 18023KT 9999 FEW008 SCT035 13/11 Q1002 TEMPO RA BKN015
EGJJ 081120Z 18016KT 9999 FEW008 SCT012 BKN035 13/11 Q1001 TEMPO RA BKN015
Bournemouth - R08/26
EGHH 081050Z 19021G32KT 9999 SCT017 BKN027 13/12 Q0999 RERA
EGHH 081120Z 18021G32KT 9999 SCT018 BKN030 14/12 Q0998
Southampton - R02/20
EGHI 081050Z 19013G32KT 150V230 9999 BKN020 13/09 Q1000
EGHI 081120Z 19012G28KT 140V230 9999 BKN022 13/09 Q0999
Newquay - R12/30
EGHQ 081050Z 24022G32KT 9999 SCT020 11/08 Q0996
EGHQ 081120Z 24021KT 9999 SCT022 11/07 Q0996
Exeter - R08/26
EGTE 081050Z 20014KT 9999 FEW010 SCT025 12/10 Q0996
EGTE 081120Z 19012KT 9999 SCT028 12/10 Q0996
Bristol - R09/27
EGGD 081050Z 18016KT 6000 RA FEW005 SCT006 BKN009 11/10 Q0995
EGGD 081120Z 17021G32KT 9000 RA FEW005 SCT006 BKN009 11/10 Q0995
Cardiff - R12/30
EGFF 081050Z AUTO 19013KT 9999 FEW023/// //////TCU 12/10 Q0995 RERA
EGFF 081120Z AUTO 19009KT 9999 SCT021/// //////TCU 12/10 Q0995
And finally at destination
Birmingham - R15/33
EGBB 081050Z AUTO 14012KT 6000 -RA SCT007/// BKN010/// OVC015/// 09/09 Q0996 RERA
EGBB 081120Z 14013KT 4000 RA FEW006 BKN012 BKN020 10/09 Q0996
We're not talking medium to long haul operations here as Landflap alludes to, we're talking short haul, regional flying (no sh** Sherlock) where a suitable airfield "should" generally be within 15 minutes flying time regardless of where you are, but ask yourself this, was this situation an engine failure? Of course not. Was it a precautionary shutdown? Of course it was. Was the engine available should they needed it in a dire situation? Of course it was. They elected to go to BHX based on the information presented to them, was this a bad decision? I think not, but if you think it was then I'd love to hear why.