To my surprise, I also did not find other studies on British English. There are quiet some (and early) ones on American English though. Here I list the earliest ones I have come across. Maybe they will help a little bit. Ah... I don't know.

Does anyone know some references on the difference between British and American stops? That would also help I guess.

Lisker, L. (1957). Closure duration and the intervocalic voiced-voiceless distinction in English. Language, 33(1), 42-49.

Lisker, L., & Abramson, A. S. (1964). A cross-language study of voicing in initial stops: acoustical measurements. Word, 20(3), 384–422.

Lisker, L., & Abramson, A. S. (1967). Some effects of context on voice onset time in English stops. Language and speech, 10(1), 1–28.

Lisker, L. (1972). Stop duration and voicing in English. Valdman, Papers in linguistics and phonetics to the memory of Pierre Delattre, 339–343.

Lisker, L. (1975). Is it VOT or a first-formant transition detector. Journal of the Acoustical Society of America, 57(6), 1547–1551.

Lisker, L., Liberman, A. M., Erickson, D. M., Dechovitz, D., & Mandler, R. (1977). On pushing the voice-onset-time (VOT) boundary about. Language and speech, 20(3), 209.

Diehl, R. (1976). Feature analyzers for the phonetic dimensionstop vs. continuant. Perception & Psychophysics, 19(3), 267-272. doi: 10.3758/bf03204180

Lisker, L. (1978). In qualified defense of VOT. Language and speech, 21(4), 375.

Thank you, Junru Wu.

I also struggled finding BrE related studies on this, but here is at least one http://www.samkirkham.com/pdf/kirkham2011icphs.pdf, though the variety is rather different from that analysed in Docherty. 

It so happens I am looking into the fortis-lenis contrast in Aberystwyth English, so a variety of British English, but again a rather different one from that analysed by Docherty. Both voicing and post-aspiration seem to matter and VOT wouldn't give me the full picture. Regarding Welsh English, I came across a lot of impressionistic comments, but that seems about it.