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In 36 instances structural rat proofing was carried out by owners or occupiers. Incidental
rat and mouse proofing in the nature of the removal of harbourage provided by unnecessary and
undisturbed accumulations received detailed attention, and in this respect the assistance given
by the Director of Public Cleansing and his Inspectors was invaluable.
The downward trend of rat infestation manifest in recent years has continued and a further
decline in the number of infestations found and treated, and the numerical quality of the same has
been experienced.
Although there was a slight increase in the major classification, (20 rats or over), 3 infestations
as against 2 the previous year, they were borderline infestations just qualifying for that
category. In the minor classification there was a reduction of 8%. 50 as against 54 in 1958.
Of the 53 rat infestations which were the subject of control measures, only 21 were of Ship
(Black rat) character, this being the lowest figure yet recorded, and in each instance the infestation
was minor. In the past the Ship rat has always been the dominant infestation and 90% of
infestations were of this nature.
Prior to and after the war this specie was firmly established in the City, and indeed, the
whole riverside of the riparian Boroughs. In 1944 it would have been true to say that very few
properties in the City were free of this type of infestation. The older properties, multi-storied,
centrally heated and non-residential, war damaged, and interspersed with restaurants, canteens
and other sources of food, were specially conducive to ship rat infestation. Haphazard and
sporadic control measures were totally ineffective and in many instances occupiers regarded
such infestation in City premises as inevitable.
From 1944 onwards organised control measures and systematic inspection was instituted.
Many established reservoir infestations were gradually eliminated, and in succeeding years the
decrease in the numerical density of ship rat and, more recently, the distribution, became
apparent.
To illustrate further the decline in rat infestation, the following summary collated from
detailed information kept since 1944, and the graph is included as a useful record.

In reviewing the present position of Ship rat infestation in the City a general perspective is
necessary, the City having boundaries with five Metropolitan Boroughs, plus a considerable riverside
frontage of wharves and warehouses. It is therefore necessary to go beyond one's own
boundaries or particular sphere of influence and envisage the situation as a whole when assessing
the relative factors which have contributed to the position now obtained.
Among the foremost of these are, the diminution of re-infestation from outside sources, the
great improvement in hygiene, progressive building construction, and improved control measures.
Regarding the question of re-infestation from outside sources there is little doubt that in the
earlier years, established infestations of ship rat were augmented from outside, principally via
shipping and river lighters, and to a much lesser degree road transport.
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