https://www.reactionengines.co.uk/ne...ulsion-systems
The Ministry of Defence intends to place a £10M contract to develop hypersonic propulsion systems for increased aircraft performance and capability.Defence Equipment and Support’s Technology Office intends to place a circa 2-year, single sourced contract, of approximate value £10M, for a UK programme to undertake design studies, research, development, analysis and experimentation relating to high-Mach advanced propulsion systems. The contract will be with Rolls-Royce Plc, (RR) and its technology partners, BAE Systems and Reaction Engines and will focus on enabling technologies for increased aircraft performance and capability.
The announcement might be
PR but it's getting spent with RR and REL and will let them crunch the numbers to see if precoolers could enhance conventional jet engines (perhaps whatever engine the Tempest might use) and, I speculate, to work out what a hypersonic platform based on SABRE might be capable of. This is all based on existing work that's already happening. There have been long-range hypersonic aircraft studies like LAPCAT that have been done already with its SCIMITAR engine. There are multiple studies going on for 2 stage to orbit launchers which are based on combat aircraft-size aircraft first stage using the REL engine. I think this is just another fork in the tree of different applications that are being looked at for the smallest size-SABRE engine. So I don't think 100s of millions are needed at this point.
I forgot to mention that they are also studying a hypersonic business jet. It would be extremely expensive probably but you can imagine that such a development might provide a neat stepping stone to something with a military purpose. A government might not have to pay for the whole thing if it can breathe just enough life into it to get it to the point where there was useful commercial interest.