Clearly an adult Tawny.
In addition to the median covert feature there are other clues, namely 1) the short, rather broad supercilium vs narrow, long and tapering in LBP, 2) the combination of dark moustachial and malar + distinct submoustachial stripes vs weak or absent moustachials and malars=less well-defined submoustachials in LBP, 3) whitish underparts vs more saturated, cinnamon buff underparts in LBP and 4) white outer tail feather vs buff or grey-toned in LBP.
Structurally, Long-billed is bulkier, longer-billed and longer, fuller-tailed than Tawny with shorter legs giving the bird a subtly different jizz.
Grahame