And that's one of the many reasons why I will NEVER travel with ba - particularly from Thiefrow.
Today I flew LH to BHX. From touchdown to leaving the car park took 35 minutes. It'd probably take that long from touchdown to stand at LHR - and, of course, there would be several orbits of Lambourn or wherever preceding the landing and subsequent taxying farce.
Why on earth does anyone with any other choice still use LHR? It's an utter shambles.