Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Episode | Broadcast date | Guest(s) | Singer(s) | Ratings |
| --- | --- | --- | --- | --- |
| 1.0 | 14August2012 | Michael McIntyre and Alex James | Amy Macdonald | 1.44m |
| 2.0 | 21August2012 | Barbara Windsor and Heston Blumenthal | The Overtones | Under 1.39m |
| 3.0 | 28August2012 | Sarah Millican and Grayson Perry | Newton Faulkner | Under 1.39m |
| 4.0 | 4September2012 | Jason Manford and Neil Morrissey | Ronan Keating | Under 1.25m |
| 5.0 | 11September2012 | Emilia Fox and Steve Backshall | Tom Jones | Under 1.37m |
Question:
when was the episode on which barbara windsor and heston blumenthal guest starred broadcasted
Answer:
21August2012