▁ax le , ▁it ▁was ▁un success fully ▁rac ed ▁by ▁May ▁C un l iffe ▁in ▁ 1 9 2 7 . ▁ ▁By ▁ 1 9 2 8 , ▁B irk in ▁had ▁come ▁to ▁the ▁same ▁conclusion ▁that ▁the ▁future ▁lay ▁in ▁getting ▁more ▁power ▁from ▁a ▁l ighter ▁model , ▁by ▁fitting ▁a ▁super char ger ▁to ▁the ▁ 4 ½ ▁lit re ▁Bent ley . ▁When ▁Bent ley ▁Mot ors ▁refused ▁to ▁create ▁the ▁super charg ed ▁model , ▁B irk in ▁determined ▁to ▁develop ▁it ▁himself . ▁ ▁Development ▁B irk in ▁set ▁up ▁his ▁own ▁engineering ▁works ▁for ▁the ▁purpose ▁of ▁developing ▁the ▁car ▁at ▁Wel w yn ▁Garden ▁City , ▁H ert ford shire . ▁With ▁financial ▁backing ▁from ▁Dor othy ▁P aget , ▁a ▁wealth y ▁horse ▁racing ▁enthus iast ▁finan cing ▁the ▁project ▁after ▁his ▁own ▁money ▁had ▁run ▁out , ▁and ▁technical ▁help ▁from ▁C live ▁Gal lop , ▁B irk in ▁engaged ▁super char ger ▁special ist ▁Am her st ▁Vill iers . ▁Mer cedes - B enz ▁had ▁been ▁using ▁compress ors ▁for ▁a ▁few ▁years . ▁ ▁In ▁the ▁purs uit ▁of ▁power , ▁the ▁ 4 ½ ▁Lit re ▁Bent ley ▁engine ▁had ▁a ▁distinct ▁advantage . ▁A ▁single ▁overhead ▁cam sh aft ▁actu ated ▁four ▁val ves ▁per ▁cyl inder , ▁incl ined ▁at ▁ 3 0 ▁degrees , ▁a ▁techn ically ▁advanced ▁design ▁at ▁a ▁time ▁where ▁most ▁cars ▁used ▁only ▁two ▁val ves ▁per ▁cyl