Went to CW today with an online appointment (evidence by a printout of the appointment). In and out with extension in 40 minutes.
The documents I handed over were:
1. Passport 2. Copies of its main page, the visa, last extension, last entry, TM47 (90 days). 3. Completed application (TM7) with photo attached.
4. Bank letter dated today with 3-month statement attached. 5. Bank book. 6. Copies of bank book pages, showing withdrawal today. 7. Copy of house owner's ID. 8. Copy of house owner's house registration. 9. Tenancy agreement. 10. Copy of tenancy agreement. 11. Hand drawn map showing route from house to CW. 12. Signed copies of the 3 additional forms that are now routinely required - "Criteria for consideration", "Acknowledgment of terms" and "Acknowledgment of penalties".
I had a TM30 signed by the house owner, but was told it was not required.
N.B. About 6 months ago, my old bank book was full so the bank issued a new one. At about the same time, I got a new passport. When I went to CW to have the visa entered into the new passport, the IO wanted to see the old and new bank books. I asked why and she explained that their regulations required this to ensure that the bank balance had remained correct since the last extension. Luckily, I had both books with me. Today, the IO who was checking the documents of those with an online appointment said that I had to produce the old bank book (or a statement from the bank, if I no longer had the old book) because "It's the regulations". I did not have the old book and pointed out three times that I had produced it when my new passport was shown to Immigration in accordance with their regulation. Eventually she took me to her superior who seemed to accept that having to produce a deceased bank book twice was overkill.
Apart from the hitch over the old bank book, a good experience.