The opening pages of RK's autobiographical 'Something of Myself'
mentions his ayah (Portuguese Roman Catholic) who I think must have come from Goa with a mother-tongue of Konkani and have been reasonably fluent in Hindustani and  English; his Hindu bearer Meeta , with a mother- tongue of Hindi or Gujerati would (in Lockwood's household) have had an ability to communicate  in basic English.
It is interesting to note that RK was enjoined to speak English to Papa and Mamma by the servants.So his cradle language was (I suggest )Hindustani,that elegant, broad based and expressive language of the Raj. More akin perhaps to Urdu than to Hindi ? I would also suggest that RK retained a reasonable fluency.I base this statement on the following :His works are generously  peppered with vernacular expressions and words to great effect. Example: read 'Gunga Din'  where he takes 'hitherao' (come  here) and rhymes it with 'panee lao' (water bring) to produce an interesting atmospheric effect. When thirst became intolerable  to the troops ( in the poem)    RK  says (through one of his soldiers):
' you put some juldee (quick) in it'  (grammatically questionable -but very effective ) 'Or I'll marrow (from the verb - mar dalna -to kill)you this minute' His Anglo-Indian ( in the original meaning of the phrase) readers would have known exactly what situation he was describing.

The entry in his autobiography goes on: " So one spoke 'English' haltingly translated out of the vernacular idiom that one thought and dreamed in" -  page 1 of Kim ? 
 
As always I find the questions and statements made on the Kipling mailbase, interesting, stimulating, mildly provocative, but above all providing an excellent excuse to delve into RK's masterly works.
 
With due deference  to that superb source of knowledge ENCARTA.
May I ask:
How many Bangladeshi's in a Dakar market place  would put their  hands up when asked the question:

Yahin koi Urdu bolne wala admi hai ? 
 
On a lighter note relevant to the languages of the sub-continent. I recall an appalling series of 'fractured English/Hindustani' phrases popular with the British Army in India - similar in a very loose way to the 'Franglais' items in 'PUNCH' of some time ago.
 
'Coldstream Guards' = Tunda panee chowkidars
Tunda -Cold
Pannee -Water
Chowkidar - Watchman.
 and
 'Tum lakri,lakri tum!' -  'You would, would you ?'
 
Tum - you (non honorific)
Lakri - wood(timber)
 
With presumption, I think RK would have found these mildly amusing.
 
Regards
Michael Jefferson