From your situation, it actually depends on how you are filing your taxes for that year particularly.
For instance, if you are filing taxes in Canada, then you have to show this income as employment income or self-employed income depending on the work.
However, if you are filing taxes in the united kingdom only, then you have to show this income as "income from Foreign sources".
Also, If you are filing taxes in both countries separately, then make sure you apply for the "foreign tax credit" to one of the countries so that you do not have to pay taxes two times on the same income in both countries.
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