If they're marked as 44, that's technically a 10. 43 is a UK 9, and a 42 is a UK 8. As the Paris points system work essentially on an imperial system, is never matches fully to a UK Metric system. It's all incremental. Go with what fits generally.
If you measure internally, from the centre of the heel to the centre of the toe the following applies
262mm - UK 8
270.6 mm - UK 9
279.2 mm - UK 10
If they're marked as 44, that's technically a 10. 43 is a UK 9, and a 42 is a UK 8. As the Paris points system work essentially on an imperial system, is never matches fully to a UK Metric system. It's all incremental. Go with what fits generally.
If you measure internally, from the centre of the heel to the centre of the toe the following applies
262mm - UK 8
270.6 mm - UK 9
279.2 mm - UK 10
Hope that helps a little.