(Adds detail, consensus forecast.)

By Ian Walker

LONDON--Wincanton PLC (WIN.LN) said Thursday margins have remained under pressure in the Pullman fleet services business in the second half of the year, but overall the group continues to trade in line with expectations.

The company, which operates distribution services in the U.K. and Ireland, didn't give any further information on its expectations or the Pullman vehicle maintenance and repair business. However, at the time of its first-half earnings last November, it said it was experiencing margin pressure on renewals within its retail and tankers & bulk sectors, citing the "highly competitive" market place in which it operates.

Margins for the specialist business, of which Pullman is part of, fell to 4.6% in the half year ended Sept. 30, 2014, compared with 5.6% in the comparable period a year earlier. However, this unit forms only 16% of group revenue.

Shares at 0945 GMT were trading down 11.87 pence, or 6.64% at 167 pence. Earlier in the session they fell to a low of 153.94 pence.

Wincanton said the changes in the price of fuel have had no material impact on the group's profitability as contractual arrangements typically pass any fuel price risk through to the end customer.

"As fuel costs are mainly a flow through cost for Wincanton, the impact of the recent fall in fuel prices is largely limited to a modest decrease in gross costs and corresponding revenues year over year," it said.

Wincanton added that there has been no significant change to the general financial position of the group from Sept. 30, 2014. At Sept. 30 it had net debt of 66.9 million pounds ($101.14 million).

For the year ended March 31, 2015 the adjusted pretax profit consensus forecast, which strips out amortization and other one-off items, is GBP28 million, on sales of GBP1.14 billion, based on five analysts estimates, according to FactSet. This compares with GBP26 million and GBP1.1 billion respectively for fiscal 2014.

Write to Ian Walker at ian.walker@wsj.com; @IanWalk40289749