Remove redundant timber beam in loft?

Background:
25 years ago Rydon Homes redeveloped a delapidated Georgian manor-house into five independent properties and built five new mews cottages onto the end. I bought one of the new-builds 18 years ago, the one that abuts the end of the five Georgian properties. Rumour has it that towards the end of the redevelopment Rydons’ profit-margin was disappearing because they hadn’t reckoned on the grand stone staircase of the central old property almost falling down. So then they brought in eastern-european cowboys to complete the new-builds cheaply. Cue for slipping coping stones atop gable-ends that hadn’t been strapped (reliant on only the mortar to hold on a 45-degree slope), missing flashing, and wrong-grade lead lining of hidden valley gutters leading to cracking and water ingress.
The issue:
Currently trying to improve insulation in loft, previous owner boarded everywhere, compressing already-thin insulation down to 7cm depth (that’s the depth of the ceiling chords of the trussed rafters). Plan is to glue-screw engineered wood I-beams along the top of the ceiling-rafter parts of each trussed rafter, lifting the floor as well as greatly strengthening bending resistance. But the loft has a hipped end, and there are two odd construction “features” in the floor of that part of the loft – first is that the direction of the ceiling joists seems unusual, instead of being at right angles to the direction of the final trussed rafter, there are three parallel (to the trussed rafters) ceiling joists, deeper (at 160mm) than those of the trussed rafters. Also there is a four-by-two-inch timber beam sitting directly above those three ceiling joists running crossways from the mid-point of the last trussed rafter to the mid-point of the stub wall where the hipped end runs out.

This beam is getting in the way, I can’t increase the height of the ceiling joists, so I need to remove this beam, or at least relocated it. Problem is I can’t fathom out its purpose. It’s definitely not a tie resisting roof-spread, because it’s not in tension and in fact it’s not even fixed at the end where it meets the stub wall, it’s just butted there tight against the wall. It’s crudely cross-nailed at the crossover-points to the three ceiling joists underneath, plus at the end where it meets the final (double) trussed rafter right by the nail-plate.
The only reason I can think of for it to be there is either as a very long (1.6 metres) nogging to keep the final trussed rafter located (unlikely) or it’s to keep the three (3.5 metres long) rafters underneath it from warping (slightly less unlikely). There is nothing fixed to the underside of the beam, the plasterboard ceiling of the bedroom underneath is 160mm clear below the beam, topped by fibreglass insulation.
The question:
Can I just rip out the cross-nails and remove this beam? That will enable me to lift the loft boarding by over nine inches and put in 300mm of insulation, then reboard higher. Thoughts?

 

Thanks Nigel, much appreciated. Like you, I'm very cautious about removing anything in my loft. But I am still puzzled by exactly what purpose that 4x2 beam serves. As I infer from your response, it seems to be there to hold in place the tops of the three ceiling joists below, to which it is cross-nailed at each crossover point. But surely there are better (or at least alternative) ways of stabilising those three joists? What about cutting that beam into tightly-fitted noggings between the ceiling joists but below the level of the existing boards, and nailing/screwing them into place?
And aren't you suspicious that the roofers who built the place were taking the line of least resistance after maybe being told by the architect/engineer as an afterthought to stabilise those three joists under the hipped end? Cue hefty lump of timber nailed into place, rather than more elegant noggings?