Retailers in Britain are warning that Brexit could start to bite in 2017 as they contend with the falling value of the pound and consumer uncertainty. 

Thursday's bumper day for retail trading updates gave an insight into how consumer spending has held up in the wake of the vote to leave the European Union in June and it wasn't as bad as some thought it might be. In general food and clothing retailers delivered modest increases in same-store sales, driving stocks higher.

Consumers may have been getting their last hooray before inflation, which is expected to hit 3%, cuts disposable income.  Britain's Office for National Statistics will update on consumer prices next Friday.

But retailers warned that the fall in the pound since the Brexit vote will likely have an impact on trading in 2017.

The pound this week fell to its lowest level against the dollar since October after comments from Prime Minister Theresa May indicated she was leaning towards a hard Brexit - one that favors immigration limits over access to the free market.

The currency was up 0.27% on Friday at $1.2186, but could be hit hard next week when May gives her first speech on Brexit Tuesday.

Clothing and food retailer Marks & Spencer (MAKSY)  Thursday reported like-for-like sales in the U.K. were up 1.3%, with clothing like-for-like sales up 2.3% and food up just 0.6%.

Investors responded favourably, pushing the share price up 2.3% on Thursday.

However, CEO Steve Rowe did warn of waning consumer confidence. Last year, the retailer said it would close 60 clothing and home stores and reposition 25% of stores to focus on food.

"Against the background of uncertain consumer confidence the business remains focused on delivering the strategic actions announced last year," Rowe said, with the company adding that it continues to "manage the business for the uncertain consumer outlook."

Department store John Lewis, a partnership owned by its employees, warned extensively of hardship in 2017, saying that trading profit will be under pressure due to changes in the retail sector. "We expect those to quicken, especially in the next 12 months as the effects of weaker sterling to feed through," the company said.

It reported like-for-like sales were up 2.8% at its grocery store, Waitrose, and John Lewis, its department store, saw sales increase 2.7% compared with the same time period last year. John Lewis anticipates margins will suffer in 2017 due to deflation in prices but increased costs due to the fall in the pound.

"The rate of retail market sales growth may slow and the rate of profit growth that is achievable will be affected by margin pressure," the company said.

The FTSE 350 General Retailers Index was up 0.65% on the day at 2,506.30. The index has lost 5.16% since August 2016. The FTSE 100 has gained 9.77% over the past six months. The stock on Friday was up 0.77% at 347.55 pence at 9:30 am GMT. Shares have lost 18.8% over the last 52 weeks.