We stayed at the Collingham apartment the last week of August and totally loved it.
Unfortunately we couldn´t meet Marga or John, but Fabio gently received us and showed the apartment, gave some advice and told us some tips about it.
It is located closer to two tube stations, to a lot of supermarkets, restaurants, pubs, etc. They also received us with beautiful flowers, wine and made a list of instructions for the appliances, useful recommendations and contact numbers. One of the things that we liked is the technology that you can experience there, for example you can listen to music while having a shower, play the electric organ, have the most delicious coffee, wash and dry all your clothes (everything with the latest technology).
We could only say positive things about our stay, and totally recommend you to rent the apartment in your future trip to London.