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You almost always need a grant of probate if there is more than £15,000 in the estate.
It depends on the bank really, but I expect you'll need a grant of probate. You see, technically, the authority to deal with the estate arises from the will itself, not the grant of probate. The probate is "confirmatory" meaning, it's just the Court confirming that somebody has been validly appointed under the will.
Technically, therefore, probate isn't "needed" for anything, but in reality, banks and other third parties want the protection of the Court under, just in case anything goes wrong, like a challenge to the will or something like that. So, in short, it depends on the bank, but for the sum of £25,000, probate is likely to be required.
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