do the immigration officers record your answers on their system when they start questioning you at heathrow airport? (just wanted to see if what you currently say on entry at heathrow to the immigration officer isn't linked to what you say on your future visits. ie. will they have things on file?)
If the stamp you are given has hand writing in it from the IO (rather than being fully pre-printed) then it is very likely that there are notes of what you said. For endorsements like this the IO will make notes on the large blank space on the back of the landing card you completed. The card then gets microfilmed.