Govt spending cannot continue on indefinietely. 2008 crash forced a rethink in spending but even then the reality is the service is living beyond its means. Current Govt is spending like there is no tomorrow BUT reality is bailiffs will be at the door looking for loans to to serviced.... note serviced not repaid.
UK Govt debt is now higher than GDP and this is before the Brexit shock to the economy.
Gordon Brown in building 2 carriers has hamstrung UK military with an expense that will take years to unwind because reality is £100 billion project has starved everything else of funding.
My guess based on current situation is by 2023 both carriers will be tied up in port for 90% of the year.