I have heard that the new male 'Bukavu' who arrived from Europe early in December, has been mating with all three females. So there could hopefully be some pregnancies there soon. The previous male Jitu was found to have growths on his testicles and had one removed, before relocating to Valencia in Spain. He was obviously a no-hoper for breeding.
No, they have never bred a gorilla to date. They have had several different males and females previously, but this is the first time they look to have a real chance of offspring.
I wondered what had happened to their previous male, where did the new one arrive from? sounds like he's settled in well and quite quickly too.
Below link has alot of the information on the new male and the old male http://www.zoochat.com/38/jitu-off-spain-25934/
Females N'Jema & Miliki are halfsisters, born in Apenheul 1993 & 1994. both motherraised(mothers Lobo & Dalila, father Bongo.) Neither have had any young previously. Third female 'Kena' was born 1981 at Barcelona(Snowflake x Bimvilli) she was handraised. Kena had several offspring born at Barcelona but they had to be handreared in Stuttgart Nursery. From there she has three sons now in the Paignton group and a daughter(Kera) at Bristol Zoo. New male 'Bukavu' was born in Munich in 1997 (Roututu x Bagira) He was motherreared. He came to Blackpool from the Schmiding(Austria) bachelor group.