I haven't been a GP for the past 20 years without learning an embarrassing secret or two, so I stepped carefully around the steaming piles of manure and knocked, using the secret knock of the Royal Horticultural Society.
Joe, ever suspicious of fellow orchid-traffickers (they are known for their ruthlessness, which is why the Colombian cartels have never cracked the market), opened the door an inch.
When he saw me, he tried to slam it, but too late; I had my foot in the door - a foot of iron, bolstered by a dread purpose.
'I am here, Joe,' I said solemnly, with just a hint of a threat, accidentally/deliberately kicking over an expensive flowerpot, 'to screen you for dementia.'
'Honestly, doc, I'm fine, I'm feeling great,' he protested, doing a little twerk to emphasise his animal vitality, but he had a guilty look on his face.
Admittedly, Joe always has a guilty look on his face, because he is always guilty of something.
'You may think you are well, Joe,' I said, 'but that's because we haven't investigated you enough yet.'
Apparently early diagnosis of dementia is now desirable, despite the real priority being support systems for the patients we've already diagnosed.
As Dr Martin Brunet argued recently in the BMJ: 'Dementia is big business, and there are many vested interests that stand to benefit from a rise in the number of diagnoses. Currently the use of diagnosis target rates is proving to be a highly successful strategy for politicians and industry.'
Asking patients the queen's name has become redundant, because they can Google it on their smartphones, so I prefer open questions. 'What is your favourite colour?' I asked Joe.
'Red?' he said, cracking under the strain. 'No, wait, it's blue, I meant blue!'
'Too late,' I said, coldly.
- Dr Farrell is a GP from County Armagh. Follow him on Twitter @drlfarrell.