Locum pharmacists are the guns-for-hire of community pharmacy, filling gaps where needed and keeping pharmacies open. According to the RPSGB, about 37 per cent of community pharmacists work as locums, usually for higher rates than employed pharmacists. And as locums are self-employed they can decide when and where to work: they can do as much or as little work as they desire, or even work as a locum in addition to their regular job.

So how do you become a locum? Graeme Stafford, an experienced locum pharmacist, suggests you first need to consider whether you're up to the challenge. "The first thing to think about is how long you've been qualified," he advises. "If you've been qualified a long time, you've got the confidence to put yourself in any situation.

"When you're up in front and you're the man or woman in charge, you could be asked absolutely anything," he says.

You also need to consider the basic requirements that might be expected of you. Only pharmacists who qualified in the UK are allowed to be the responsible pharmacist in a pharmacy that's been open less than three years, so if you qualified abroad you might not be able to take every job on offer. It's also very important to have indemnity insurance in case the worst happens.

Once you're sure you want to do it, there are two ways to find a position. There are several locum agencies around the country that will find placements for eager pharmacists. Agencies do not charge locums a fee - they charge the pharmacy - but will make you sign a contract and you could work in almost any pharmacy.

However, Mr Stafford recommends budding locums start with the other route: by talking to pharmacists they know. "The best way is networking," he says. "Go and see people - don't go straight to agencies and be launched into somewhere that you have no idea about."

LocumVoice, a networking website for locum pharmacists, has a guide on how to work as a locum available to members. The guide suggests you attend local meetings and get to know other pharmacists in the area. Use every opportunity to tell people you are available for locum work, and contact local multiples to find out who is in charge of arranging locum cover. The LocumVoice guide also suggests printing business cards with your qualifications and mobile details, so people can contact you easily if work is available.

Before accepting a placement, check that you know what the situation will be when you arrive. The Society has a guide to working as a locum available on its website, which includes a checklist of the key things to consider before taking on a position (see Top tips for locums, above).

Mr Stafford also advises locums to visit the pharmacy beforehand to make sure they're familiar with the layout and work processes, or they could find themselves in a tricky situation.

"I turned up once on a Saturday morning when the pharmacy was having a refit," he says. "The guys were still drilling and things were falling on to the dispensary bench. Nobody had told me. You need to ask questions. Have they got the basic books there? The internet? Some larger chains will limit access."

Mr Stafford also highlights the importance of knowing the level of training of the staff that will be present. And the responsible pharmacist rules mean a locum needs to be familiar with the pharmacy's standard operating procedures (SOPs), as they will be responsible if something goes wrong. Locums also need to consider whether they will take a break, and whether they will be contactable during that break.

Lastly, it's important to think about money. According to LocumVoice, most multiples have different ways of paying locums, and it's important not to leave before you have completed their paperwork. The LocumVoice guide recommends you keep copies of all paperwork, and a robust system of organising bookings and ensuring you've been paid for your time.

Mr Stafford suggests a typical wage for a locum is around £25 per hour, and recommends pharmacists don't work for less than £23 per hour. "Don't sell yourself short," he advises. "If they know they can get you for £18, £19 or £21 an hour, it's very hard to argue differently later."

Locums are self-employed, and will need to do their own tax and National Insurance. Self-assessment is easy, although it's possible to hire an accountant to maximise all potential savings.

As a final note, the LocumVoice guide says there is one last thing to keep in mind: "A locum pharmacist who thanks the staff for their help and says goodbye, will most likely be asked back."