All mainline train operators are classed as Level 2 responders under the Civil Contingencies Act. As a result, the terms of being granted a Safety Certificate require adequate emergency plans to cover forseeable situations that could impact service delivery. They also have to follow instructions issued under the Railways Act 1993 Sections 119 to 121. So all train companies SHOULD have had an adequate contingency for a power outage, phones down or building evacuation- it happens, and typically the contingency works.
However, the devil is always in the detail. Senior management types in most sectors (not just rail) are very keen to be told what they want to hear ("yeah its all good we pay a few peanuts to shiney provider X and they do it all"), whilst appraising contingency plan effectiveness properly needs assurance/compliance staff who tell the senior bods what they NEED to hear (errrrr.... we think there's some plausible scenarios you've not fully considered). Unfortunately, the latter scenarion can be career inhibiting especially for employed staff (those of us who do contract compliance work have it a bit easier, but you cannot assume that audit findings are always fully acted upon......

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One of my standard audit questions for a few years was "so what happens to your cloud systems if for some reason there's a bank glitch and the monthly payment doesn't go through?" Given how often supplier payment glitches happen with most organisations, its a fair question- and typically produced a look of horror as it had not been considered...... (it is typically not a disaster, but not considering it is a good indication of inadequate consideration of failure points in the underpinning systems architecture, it's a handy auditors starter question to flush this out).
TPO