I've had a look on Lewisham's planning application site. The building was locally listed (it was also in a conservation area) and the original planning application was put in in 2006. Lewisham didn't decide in time (although it states they would have refused, but because of issues with the proposed design not the demolition of the existing building) so the applicant appealed and it was the Planning Inspector who granted the application. See report here.

Apparently additions were made to the building in the late 1980s to give it a more Art Deco appearance, so it wasn't actually an original Art Deco building.

But, earlier this year the applicant applied to renew the planning permission and Conservation Area demolition consent and Lewisham refused, on the grounds that the proposed development didn't provide affordable housing in line with housing policy introduced in 2008.

So how come the building has now been demolished? The Planning Inspector's report states that planning permission would expire 3 years from the date of the planning decision, ie 14 August 2010. Development has to begin (but not necessarily be finished) before the expiration date, so if the building was demolished before 14 August 2010 then the developer would be doing so under the original planning permission.

The proposed development is for 14 2-bedroom flats and a ground-floor workshop.