ˌɔn wˈʌn dʒuːlˈaɪ tˈuː θˈaʊzənd tˈɛn, nˈoʊ. twˈɛnti wˈʌn sˈɪɾi ʌv mˈɛlbɚn skwˈɑːdɹən ɐmˈælɡɐmˌeɪɾᵻd wɪð kˈɑːmbæt səpˈoːɹt jˈuːnɪt wˈɪljəmz tə bɪkˌʌm ɐn ˈɪntᵻɡɹˌeɪɾᵻd pˈɜːmənənt ˈɛɹ fˈoːɹs ænd ɹɪzˈɜːv jˈuːnɪt ɹᵻspˈɑːnsᵻbəl fɔːɹ ˈɛɹfiːld ænd bˈeɪs səpˈoːɹt ænd ɹɪzˈɜːv tɹˈeɪnɪŋ.
On 1 July 2010, No. 21 (City of Melbourne) Squadron amalgamated with Combat Support Unit Williams to become an integrated Permanent Air Force and Reserve unit responsible for airfield and base support and reserve training.