The first attack was carried out on the Portman Hotel in Portman Square, the IRA team headed by  Eddie Butler drove slowly by the hotel and fired approximately 20 rounds of 9mm ammunition into the hotel using a Sten Submachine gun.
Two hours later another IRA team drove by the Carlton Tower Hotel located along Cadogan Place, Knightsbridge and fired shots into it this time with an M1 carbine.
Four people were injured in this attack mainly from flying glass.

At first people believed the attacks might have been motivated by anti‐Semitism as both hotels were owned by Jewish businessmen.
But police believed it to be the work of the Provisional IRA who carried out a similar shooting attack a month earlier in December 1974 against the Churchill Hotel also in Portman Square in which three people were injured.
The first attack was carried out on the Portman Hotel in Portman Square, the IRA team headed by  Eddie Butler drove slowly by the hotel and fired approximately 20 rounds of 9mm ammunition into the hotel using a Sten Submachine gun. Two hours later another IRA team drove by the Carlton Tower Hotel located along Cadogan Place, Knightsbridge and fired shots into it this time with an M1 carbine. Four people were injured in this attack mainly from flying glass.
At first people believed the attacks might have been motivated by anti‐Semitism as both hotels were owned by Jewish businessmen. But police believed it to be the work of the Provisional IRA who carried out a similar shooting attack a month earlier in December 1974 against the Churchill Hotel also in Portman Square in which three people were injured.
Carlton Tower and Portman Hotel shootings