mysql> select * from postcodes where postcode = "SW11 3NG" and address_1 REGEXP '6(\s|$)';
+----------+----------+----------+--------------+--------------+-----------------+-----------------+------------+-----------------------+--------------+----------+-------------+--------+------------------+-----------+-----------------+-----------------------+-----------+-----------+-----------+-----------+
| id       | postcode | dps_code | organisation | sub_building | building_name   | building_number | dep_street | street                | dep_location | locality | postal_town | county | full_county_name | address_1 | address_2       | address_3             | address_4 | address_5 | address_6 | address_7 |
+----------+----------+----------+--------------+--------------+-----------------+-----------------+------------+-----------------------+--------------+----------+-------------+--------+------------------+-----------+-----------------+-----------------------+-----------+-----------+-----------+-----------+
| 24013360 | SW11 3NG | 4S       |              | FLAT 76      | SELWORTHY HOUSE |                 |            | BATTERSEA CHURCH ROAD |              |          | LONDON      | LONDON | LONDON           | Flat 76   | Selworthy House | Battersea Church Road | LONDON    |           |           |           | 
| 24013371 | SW11 3NG | 4D       |              | FLAT 66      | SELWORTHY HOUSE |                 |            | BATTERSEA CHURCH ROAD |              |          | LONDON      | LONDON | LONDON           | Flat 66   | Selworthy House | Battersea Church Road | LONDON    |           |           |           | 
| 24013378 | SW11 3NG | 3U       |              | FLAT 6       | SELWORTHY HOUSE |                 |            | BATTERSEA CHURCH ROAD |              |          | LONDON      | LONDON | LONDON           | Flat 6    | Selworthy House | Battersea Church Road | LONDON    |           |           |           | 
| 24013382 | SW11 3NG | 3Q       |              | FLAT 56      | SELWORTHY HOUSE |                 |            | BATTERSEA CHURCH ROAD |              |          | LONDON      | LONDON | LONDON           | Flat 56   | Selworthy House | Battersea Church Road | LONDON    |           |           |           | 
| 24013393 | SW11 3NG | 3A       |              | FLAT 46      | SELWORTHY HOUSE |                 |            | BATTERSEA CHURCH ROAD |              |          | LONDON      | LONDON | LONDON           | Flat 46   | Selworthy House | Battersea Church Road | LONDON    |           |           |           | 
| 24013404 | SW11 3NG | 2N       |              | FLAT 36      | SELWORTHY HOUSE |                 |            | BATTERSEA CHURCH ROAD |              |          | LONDON      | LONDON | LONDON           | Flat 36   | Selworthy House | Battersea Church Road | LONDON    |           |           |           | 
| 24013415 | SW11 3NG | 1Y       |              | FLAT 26      | SELWORTHY HOUSE |                 |            | BATTERSEA CHURCH ROAD |              |          | LONDON      | LONDON | LONDON           | Flat 26   | Selworthy House | Battersea Church Road | LONDON    |           |           |           | 
| 24013426 | SW11 3NG | 1J       |              | FLAT 16      | SELWORTHY HOUSE |                 |            | BATTERSEA CHURCH ROAD |              |          | LONDON      | LONDON | LONDON           | Flat 16   | Selworthy House | Battersea Church Road | LONDON    |           |           |           | 
+----------+----------+----------+--------------+--------------+-----------------+-----------------+------------+-----------------------+--------------+----------+-------------+--------+------------------+-----------+-----------------+-----------------------+-----------+-----------+-----------+-----------+
8 rows in set (0.00 sec)

mysql> select * from postcodes where postcode = "SW11 3NG" and address_1 REGEXP '(\s|^)6(\s|$)';
Empty set (0.01 sec)

mysql> select * from postcodes where postcode = "SW11 3NG" and address_1 LIKE '% 6 %';
Empty set (0.03 sec)

mysql> select * from postcodes where postcode = "SW11 3NG" and address_1 REGEXP '(^|\s)6(\s|$)';
Empty set (0.01 sec)

mysql> select * from postcodes where postcode = "SW11 3NG" and address_1 REGEXP '6\D';
Empty set (0.01 sec)

mysql>