Last night, I was flying to EGLL attempting to land at RWY27L. I was passing just below EGLC when I was told to contact EGLC. I did and immediately asked to change frequency so that I can give my intentions to EGLL who had also asked me to contact tower. EGLC asked me what my intentions were so I asked again to request a frequency change. I was told to avoid sending duplicate messages.
How do I tell one tower that my intention is to land at another airport? wouldnt they be able to see my flightplan and see where I am trying to land, if I have it filed?