People travelling to the Grand National festival this week have been given stern advice by one train operator as thousands of people are expected to descend on Aintree for the annual horse-racing spectacle.

Travellers are being warned off attempting to travel without a valid ticket, with Northern stating “don’t gamble on it” as “chancers” will be met by teams of revenue protection officers deployed at key stations across the region – and hit with a hefty fine.

Anyone caught without a valid ticket or ‘promise to pay’ notice may be issued with a £100 penalty fare, which is reduced to £50 if paid within 21 days.

Services in and around Liverpool are expected to be busy over the three-day event and people are encouraged to allow extra time for their journey.

Mark Powles, commercial and customer director at Northern, said: “We know from experience that all major events encourage some people to think they’ll get away with not buying a ticket for their journey.

“By publicising this clampdown in advance, we hope less people will ‘chance it’ and end up £100 down before they even get to the racecourse.”

Northern is the second largest train operator in the UK, with 2,500 services a day to more than 500 stations across the north of England.

The three-day festival – from Thursday 11 April to Saturday 13 April – is one of the biggest events in the sporting calendar, attracting more than 150,000 people to Aintree Racecourse, according to Merseyside Police.

Merseyrail will be running a special timetable during the festival on its northern line, with trains every 7.5 minutes between the race course and Liverpool Central (via Moorfields) from 11.30am and 1pm and again between 4pm and 8.30pm.

Outside of these times, trains will run every 15 minutes.

Only pre-booked vehicles will be allowed onto the Aintree site and there are parking restrictions around the course, which police say will be “rigorously enforced”.

Superintendent Matthew Moscrop said: “Visitors can help the organisers and themselves by allowing extra time to get to the course.”

Fortunately, there is no planned industrial action affecting rail services during the Grand National. The last week has seen a series of rolling walkouts by members of the Aslef union that brought train lines across the country to a halt, while the same drivers also refused to work overtime. The ban on overtime came to an end on 9 April.