Go into a high street pub and you may still find the packaged snacks choice confined to a brand each of crisps, nuts and pork scratchings, but in the fast-moving world of grocery and convenience it’s become much more than that.

Kantar Worldpanel puts the UK snacks market at £41.6bn and a recent IGD report suggests the overlapping sector of food-to-go was worth £17.4bn in 2017, with a forecast that this will rise to £23.5bn over the next five years. Convenience and forecourt retailers’ share of this is expected to grow by 6.1%, from £2.7bn to £3.6bn.

There seem to be few limits to the number of category off-shoots and sub-segments, nor to the number of established categories, such as cheese and baked goods, that now vie for a piece of the action that traditional savoury snacks cornered for so long.

There’s also been a proliferation of packaging formats and price tiers, with premium brands and sharing bags among the products that have transformed the category in the past decade to fit in with consumers’ changing leisure interests and lifestyles. And growth in areas such as cheese and meat snacks has seen the category spread from the grocery shelves into the chiller cabinets.

Rob Malek, managing director of Roundswell Services on the A39 at Barnstaple in Devon, says: "Ambient snacks are slightly up and chilled snacks are showing quite a bit of growth. Because we’re fairly transient in terms of trade, the smaller packs for crisps tend to go very well rather than the bigger packs.

"There’s definite interest in free-from products and protein products. We’ve introduced some of those and they’re going reasonably well."

For traditional snacks, larger pack formats are doing better across convenience as a whole. Lynne Price, Kettle Foods business development manager, notes that the crisps and snacks category within the petrol and travel channel is up 6.5% annually with larger sharing products growing at 9.4% (IRI, to Feb 25), and says there is growing demand for premium brands.

"The sharing category is the number one growth sector thanks to the popularity of the big night in and the huge choice now available on streaming services," she says.

But other pack sizes are making their mark outside of crisps. Anca Lazar, brand manager at Dairy Crest, says a notable recent trend across the whole snack market has been retailers focusing on single-serve formats and healthier options that help consumers with portion control, typically with a premium over more traditional snack options.

"This has typically meant space expansion for snacking products at front-of-store, accommodating a wider choice of formats and product categories including bars, nuts and seed shots, savoury snacking, rice cakes, dried fruit portions and chilled snacking options such as cheese, hard-boiled eggs and meat-based snacks," she says.

Pavan Chandra, marketing manager for Peperami at Jack Link’s, says health concerns are one reason consumers are being steered towards a more diverse range of snacks. "We have seen an increase in all occasions, particularly afternoon snacking," says Chandra. "Retailers should be focusing on snacks with health benefits as protein and meat snacking becomes increasingly popular with consumers."

Seabrook Crisps commercial director Jon Wood says the whole way that people eat has driven changes in the snacks market.

"As people’s lifestyles get busier, many consumers now have less time to dedicate to eating sit-down meals and are looking for more convenient ways to fill up," he says. "As a result, consumption of food and drink on-the-go is on the rise. Meals have become more snack-like with a market response to introduce more authentic food values into the snacks", citing as an example the introduction of Lamb & Mint flavour to Seabrook’s crisps range.

Seabrook’s has linked up with Alton Towers for the theme park’s launch this year of its Wicker Man rollercoaster and is backing the sponsorship deal on-pack with a promotion for consumers to gain two-for-one entry, supported by advertising, social media activity and pos.

The promotion runs on Seabrook’s crinkle cut crisps across all pack formats and Seabrook is marking the promotion with a limited-edition Fiery Woodsmoked BBQ flavour.

Seabrook is also introducing smaller case sizes for its 31.8g bags to help retailers reduce stockholding and improve cash flow. Wood says: "We’re committed to supporting our customers and providing value and opportunities to drive sales wherever possible. The smaller cases will allow retailers to manage their stock more efficiently, giving them more space and an opportunity to experiment with different SKUs."

Price at Kettle Foods agrees that retailers need to be careful how they manage their ranges as the choice available on the market grows. "Retailers should be putting their focus into rationalising their ranges," she argues. "Consumers would prefer a wider selection of best-selling brands rather than, for example, a lightly salted variety from 10 different ones.

"Tactically placed pos, such as dumpbins, can be real growth drivers with key products, particularly around major events such as the World Cup."

The company is aiming to exploit middle-of-the-day sales this year with an on-pack promotion for consumers to win the "ultimate lunch" in Hollywood and an offer to watch a film for a £1 from streaming service Chili Cinema with every pack.

"The promotion is designed to reflect Kettle Chips’ single brand positioning as a lunch upgrade and encourage consumers to trade up when snacking on-the-go," says Price.

It has also introduced £1 price-marked packs for five of its most popular flavours and the brand as a whole is receiving above-the-line support from June in a £3m Real Food Real Pleasure campaign to reinforce the message that Kettle Chips are "developed by a chef in a kitchen, not a technologist in a lab".

Market-leading crisps producer Walkers is celebrating its 70th anniversary this year with a new pack design and six limited- edition flavours inspired by changing food tastes across the decades: Coronation Chicken from the 1950s, Roast Lamb & Mint from the 1960s, Cheese Fondue from the 1970s, Chicken Tikka Masala from the 1980s, BBQ Rib from the 1990s and Sweet Chilli from the 2000s.

It also has a campaign with ITV announcing prize winners during ad breaks in prime time Saturday night shows including Britain’s Got Talent. It is running on Mix Ups, Bugles and sharing bags.

In the sharing segment Walkers has launched Doritos Heatburst, a product where each crisp delivers two types of flavour, and Walkers Max Strong, a range of ridged crisps aimed specifically at beer drinkers.