Sustainable Development Capital (SDC) is understood to be in competition with Australian bank Macquarie as the government prepares to privatise the £4bn-valued GIB.
SDC, which is heading up a consortium that also involves the Pension Protection Fund, is understood to be emphasising its British-ness as it hopes to persuade the government that it is the suitable candidate.
The SDC will also highlight its track record and interest in sustainability.
The Sunday Times has reported that Macquarie is set to table a final round offer for GIB on Monday.
Macquarie and the SDC have declined to comment.