Improbable as it might seem, William Lyons’ XK120 Super Sports, revealed at the 1948 Earls Court Motor Show, was a lash-up job. With styling scribbled out in two weeks, and hastily constructed from aluminium panels over a wooden frame, it was built on a cut-down MkV chassis to showcase the new DOHC engine. 

However, the good looks proved an enormous hit and in 1950 the 120 went into full-scale production with a steel body and alloy bonnet, doors and boot lid. The 120 OTS (Open Two-Seater) was joined by a Fixed Head and Drop Head Coupé.

In 1954 the XK evolved into the 140. The engine was moved further forward, freeing up much-needed interior space and allowing for small rear seats. While the cabin looked a bit stretched, the car was more refined. Burman recirculating-ball steering was changed for an Alford and Adler rack-and-pinion set-up, the rear lever arms were replaced with telescopic dampers and the cooling system was improved. The XK140 was offered as a Fixed Head, OTS and DHC.

The plumper XK150 (also in FHC, OTS and DHC) was launched in 1957 with the much-vaunted disc brakes. Refinement continued and power increased thanks to the S option with its triple SU carbs: the final 3.8S whacked out a claimed 265bhp.

Ian Mills of Twyford Moors has been in the XK restoration and sales business for decades. 

‘Drop Head Coupés have always been more popular because they are the most practical models,’ he says. ‘Open but with a proper hood, unlike the OTS. The 140 Fixed Head is the most popular for enthusiasts who want to use their Jaguars on tours. Values start around £45,000. The 120 OTS is for the purist and the 120 Fixed Heads are rare: well restored, a 120 FHC is at least £75,000. The 3.8 XK150S has shot up in value to over £100k. 

‘As a regular driver, the 3.4 XK150 is undervalued at about £35k. It is a lovely car that will cruise in comfort at 90mph all day.’

‘Drivers who buy Jaguar XKs usually take them on long touring trips,’ says Ian Mills. ‘Therefore, most want solid cars with a few subtle modifications. Our fast road option with a five-speed gearbox conversion is popular. Front disc brake conversions make the vehicles safe on motorways and upgraded cooling is essential: a fresh radiator and electric cooling fan are worthwhile. An ally rad is needed only for racing. 

‘Rebushing the suspension and adding decent dampers makes a great deal of difference, and we have a neat rear spring bushing upgrade that really helps sharpen the handling. Retrofitted (for the XK120) or rebuilt rack-and-pinion steering is a great help, although most customers find the solid-mounted rack option too jarring.’

Mills continues: ‘Check the lower 18 inches of the bodywork because repairs are time-consuming and therefore expensive. The chassis is tough yet rust can affect the anti-roll bar mounts, rear spring hangers, back section above the axle and rear chassis legs. The sills go where they join the B-posts.

‘For regular use, electronic ignition is much more reliable – we use the 123 Ignition distributor – along with an alternator conversion. Although purists might not agree, radial tyres are most suitable for motorway and general driving conditions.’

He concludes: ‘The really good thing about XKs is that they are tough, simple and virtually all the parts are available. You can enjoy one in original spec or have it upgraded to your requirements.’

XKs have long been used for racing, rallying and touring. Prices have always been pegged above those of E-types because XKs are eligible for more events and appreciated by well-heeled buyers. However, over the last decade values have become very strong. Decent examples range from £45,000 to £230,000 depending on spec and provenance. 

The problem Ian Mills at Twyford Moors and other specialists face is a lack of stock. Most owners keep the cars and invest in improvements. If you want an XK totally rebuilt, a nut-and-bolt job will cost you in the region of £100,000 plus the donor car. But because XKs are rugged and relatively simple they can be renovated on an ongoing basis, and the few mods that make them really enjoyable to drive are less expensive to enact than on other similar British classics of the period. Properly sorted, an XK is refined enough to use for pottering to the shops and fast enough to drive to the south of France.