‘14 . The first limb provides that the effect of a reasonable excuse is to deem non-failure up to the time the excuse ceases. Separately, the effect of the second limb is to deem non-failure after the excuse has ceased if the person in question does what is required to be done without unreasonable delay. The second limb provides a separate relief from that in the first limb; it is not an additional hurdle to be overcome for the application of the relief under the first limb.’
‘15.A deemed non-failure under the first limb ceases to be regarded as a non-failure with effect from the cessation of the excuse (for the future but not retrospectively), and that failure from that time can only be regarded as non-failure if the necessary action, in this case the making of the returns, is taken without unreasonable delay after the excuse has ceased.’