By Jennifer Hill

LONDON (Reuters) - First-time buyer numbers have fallen to the lowest level in almost three decades, research from Britain's largest mortgage lender shows.

An estimated 300,000 first-time buyers entered the housing market in 2007 -- the lowest level since 1980 and 44 percent less than in 2002, according to the Halifax.

Those vying to get a foothold on the housing ladder cannot afford to buy the average house in 96 percent of towns across the UK, up from just 30 percent five years ago, its fifth annual housing review shows.

Terraced property -- traditionally the least expensive property type -- was unaffordable in 71 percent of towns, compared to just 11 percent in 2002.

The review tracks housing affordability in 483 towns, including 32 London boroughs.

A town is classified as unaffordable if the ratio of house prices to first-time buyer household income is above four.

The average price paid by a first-time buyer rose 15 percent to 175,093 pounds in 2007, up by 82 percent from 95,994 pounds in 2002, the figures show.

Henley on Thames, where the average property price is 13.1 times the average income of a first-time buyer, was found to be the least affordable area.