If.....
If I read this correctly Mauler was a SARH missile, not a beam rider as stated elsewhere. Such as on the Wiki page.
If I read this correctly the VSR set was a L-band stacked beam type using the 'modern' flat antenna.
If I read this correctly the TIR set was FMCW, using separate transmit and receive dishes (of differing size).
If I make out the missile, it's not the same appearance as that in BSP. More like the Falcon type or in fact the HAWK.
I can also see why it fell, trying to squeeze HAWK-like capabilities of system into something at best 30% the size.
In turn by reading this I can seen why the UK might have proposed PT.428 and why....
In that it likely used the same FMCW type system for TIR, but for beam riding guidance obviating the issues of clutter complicating the seeker systems job.
I can also see why PT.428 is using two versions of missile, one unboosted and one boosted, to overcome the variables in target speed and in missile weight for the unboosted version.
If anything the US effort is just too advanced, particularly in miniaturisation.