Question

To ask Her Majesty’s Government what assessment they have made of the case for the civil timescale Greenwich Mean Time being renamed Greenwich Meridian Time, with a value of UT1 at longitude zero based on GPS rather than the historic location of the prime meridian.

As the reference frame for the Global Positioning System (GPS) is established through a mathematical interpretation of satellite radio signals, rather than a physical meridian, it is not conceptually appropriate to represent it in the same way as other meridians have historically been marked at Greenwich.

We do not see any practical benefit in changing the reference point for UT1 even if it was a decision the UK Government could make unilaterally. Such a change could cause confusion as could use of the term “Greenwich Meridian Time”. In line with the International Telecommunication Union Radio Regulations, all time‑signal broadcasts in the UK transmit. the international timescale UTC, and so any change to UT1 or GMT would have no impact on the time-signal available to the UK public.