The calculations for magnetic declination (to allow maps to be orientated to magnetic north) reply on predictive models that only maintain sufficient accuracy for 5 years. The last model expired at the end of 2024 but the new model has now been installed so should be good until 2030, unless the magnetic poles become even more unpredictable. The model is produced by the United States’ National Geospatial-Intelligence Agency (NGA) and the United Kingdom’s Defence Geographic Centre (DGC) – more details here.