hi
the only birth i can find using both london and middlesex as a search is for this one for kathleen annie e haynes reg dist holborn vol 1b p 634 year 1897 , the nearest after that appears to be for kathleen doris haynes reg dist st giles vol 1b p 556 year 1900
i did also find a death reg for a kathleen a haynes age 33 reg dist brentford vol 3a p 165 .
but i must stress this info is pure speculation and should be taken on face value only not fact until investigated further .
so far i can,t find any more definate info for the dear lady your helping and as nanny jan has said it looks like you need a look either in southend library or essex archives or even essex family history soc for more detailed info ,but it,s like the needle and haystack scenario .
regards
trevor