The change window is not a preference here, it is an obligation with a notification period attached. So the window sets the shape of the work rather than the other way round, and everything is designed to be reversible inside it.
What we do here
The lines that matter most in this sector, and why.
Estate assessment
Regulated estates hide systems inside other systems. The count is almost never the count on the org chart.
Modernization
Behind a facade, capability by capability, with reconciliation evidence produced at every step.
Migration and cutover
Rehearsed against production-shaped data, with a rollback timed to fit inside the contractual window.
Decommissioning
With the retention schedule agreed by legal and compliance before anything is extracted.
The batch is still nightly
The window sets the plan. Everything is reversible inside it.
The batch is still nightly
Modernizing around a batch that cannot move means the window sets the unit of work, not the architecture. We size each change to what can be completed, reconciled and evidenced before the batch starts, and if something will not fit we split it rather than asking for the window to stretch.
What we plan around
| Constraint | How the plan absorbs it |
|---|---|
| The nightly batch | Work is sized to complete and reconcile before it starts, never to overlap it |
| The contractual window | And its notification period, which is usually the real constraint on the date |
| Reconciliation evidence | Produced as the work proceeds rather than assembled afterward for an auditor |
| The auditor's read of a rollback | A rollback that has been executed and timed reads very differently from one that has been written down |
Questions we are always asked
Four of them, answered the way we answer them on the phone.
Can you work inside our change window?
The window is the first input to the plan, not a constraint discovered late. Every step is sized so it completes and can be reversed inside one, because a step that needs two windows is really an outage with a gap in it.
What about the nightly batch?
It is treated as fixed. Modernizing around a batch that cannot move is the normal case here, and a plan that begins by asking for the batch to change is a plan that will not be approved.
Do you need production data?
We need production-shaped data, which is not the same thing. Rehearsals run against volumes and distributions that match production, so the timings mean something without the data itself leaving your controls.
How far ahead do you need the window booked?
Further than feels necessary, and it is written into the plan on day one alongside the notification period. Cutovers here fail on paperwork lead times far more often than on engineering.
Case studies
Programs in this area, described by what they were rather than by who paid for us.
