hi sparrow89
i lost my passport and applied for my duplicate passport in may 2012; i got my duplicate passport in about 18 days; but this was because i had an emergency situation; i had my wedding and i had to leave to India; i had sent an email to somebody called TARA CHAND; he is the first secretary (consular);
fs.cons@hcilondon.in ; he understood my situation and he helped me; the passport i recieved had avalidity of 1 year
if there is no higher authority intervention like this I am just wildly guessing maybe 6 weeks should be sufficent; when i gave the filled up application-the man in the counter asked to call me after 3 weeks; i dont know what for; when asked he said just to check teh status
i met a few persons who had not recieved their duplicate passports even after 45 days; but i guess maybe they were exceptions; if i remember correctly i knew some people said in online forums they got theirs in 4 weeks
but do you need a passport urgently? do you have an emergency situation? like a wedding or a visa renewal due? if so use this email id and communicate with tara chand; i hope he still is the first secretary; even if not so somebody else will be there
please let me know so that i could help you if required