wrote:

My attempts at getting a response from either manufacturers or the
Suffolk fire service have failed completely so far. Maybe I could try
London fire service as the flat is in London.

The trick is to spell ionisation as ionization when googling :-). Then
you get advice such as this, from
http://www.dps.state.mn.us/fmarshal/...etectors.html:

IONIZATION VERSUS PHOTOELECTRIC DETECTORS

In cases where smoke detectors are subject to frequent false alarming
due to cooking, smoking or similar causes, the State Fire Marshal
encourages the installation of photoelectric smoke detectors as they
are not as susceptible to these types of false activation.

Studies have shown that ionization detectors are better at detecting
small, invisible particles of combustion that are typically present
from fast, hot, flaming fires. These studies have also shown that
photoelectric detectors are better at detecting larger, visible smoke
particles that are more commonly seen from slow, smoldering fires. Both
types of smoke detectors have been shown to be effective in detecting
typical residential-type fires. Some research seems to indicate that
photoelectric detectors may activate slightly sooner as many
residential fires start out as slow, smoldering fires.

So photoelectric appears to be the way to go...

Ben.